Merge branch 'ported-moebius'

109 files changed, 2894 insertions, 299 deletions

diff --git a/config/milestone.txt b/config/milestone.txt
index 05d41f934..27f2d007f 100644
--- a/config/milestone.txt
+++ b/config/milestone.txt
@@ -10,4 +10,4 @@
 # hardcoded milestones in the tree from these two files.
 #--------------------------------------------------------
 
-4.1.0
+4.1.1
diff --git a/devtools/client/webconsole/test/browser_webconsole_strict_mode_errors.js b/devtools/client/webconsole/test/browser_webconsole_strict_mode_errors.js
index c8f2200f9..cdaf2764e 100644
--- a/devtools/client/webconsole/test/browser_webconsole_strict_mode_errors.js
+++ b/devtools/client/webconsole/test/browser_webconsole_strict_mode_errors.js
@@ -55,7 +55,7 @@ add_task(function* () {
     webconsole: hud,
     messages: [
       {
-        text: "TypeError: setting a property that has only a getter",
+        text: 'TypeError: setting getter-only property "p"',
         category: CATEGORY_JS,
         severity: SEVERITY_ERROR,
       },
diff --git a/dom/base/Element.cpp b/dom/base/Element.cpp
index 886acc670..9ced64c0d 100644
--- a/dom/base/Element.cpp
+++ b/dom/base/Element.cpp
@@ -165,10 +165,9 @@ nsIContent::DoGetID() const
 }
 
 const nsAttrValue*
-nsIContent::DoGetClasses() const
+Element::DoGetClasses() const
 {
   MOZ_ASSERT(HasFlag(NODE_MAY_HAVE_CLASS), "Unexpected call");
-  MOZ_ASSERT(IsElement(), "Only elements can have classes");
 
   if (IsSVGElement()) {
     const nsAttrValue* animClass =
@@ -178,7 +177,7 @@ nsIContent::DoGetClasses() const
     }
   }
 
-  return AsElement()->GetParsedAttr(nsGkAtoms::_class);
+  return GetParsedAttr(nsGkAtoms::_class);
 }
 
 NS_IMETHODIMP
diff --git a/dom/base/Element.h b/dom/base/Element.h
index 5d878df60..cf1d197e2 100644
--- a/dom/base/Element.h
+++ b/dom/base/Element.h
@@ -544,6 +544,18 @@ public:
   virtual uint32_t GetAttrCount() const override;
   virtual bool IsNodeOfType(uint32_t aFlags) const override;
 
+  /**
+   * Get the class list of this element (this corresponds to the value of the
+   * class attribute).  This may be null if there are no classes, but that's not
+   * guaranteed (e.g. we could have class="").
+   */
+  const nsAttrValue* GetClasses() const {
+    if (HasFlag(NODE_MAY_HAVE_CLASS)) {
+      return DoGetClasses();
+    }
+    return nullptr;
+  }
+
 #ifdef DEBUG
   virtual void List(FILE* out = stdout, int32_t aIndent = 0) const override
   {
@@ -1372,6 +1384,12 @@ protected:
 
 private:
   /**
+   * Hook for implementing GetClasses.  This is guaranteed to only be
+   * called if the NODE_MAY_HAVE_CLASS flag is set.
+   */
+  const nsAttrValue* DoGetClasses() const;
+
+  /**
    * Get this element's client area rect in app units.
    * @return the frame's client area
    */
diff --git a/dom/base/FragmentOrElement.cpp b/dom/base/FragmentOrElement.cpp
index 293177ce7..79f6cff51 100644
--- a/dom/base/FragmentOrElement.cpp
+++ b/dom/base/FragmentOrElement.cpp
@@ -574,6 +574,9 @@ FragmentOrElement::nsDOMSlots::Traverse(nsCycleCollectionTraversalCallback &cb,
   NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mSlots->mChildrenList");
   cb.NoteXPCOMChild(NS_ISUPPORTS_CAST(nsIDOMNodeList*, mChildrenList));
 
+  NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mSlots->mLabelsList");
+  cb.NoteXPCOMChild(NS_ISUPPORTS_CAST(nsIDOMNodeList*, mLabelsList));
+
   NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mSlots->mClassList");
   cb.NoteXPCOMChild(mClassList.get());
 
@@ -602,6 +605,7 @@ FragmentOrElement::nsDOMSlots::Unlink(bool aIsXUL)
   mShadowRoot = nullptr;
   mContainingShadow = nullptr;
   mChildrenList = nullptr;
+  mLabelsList = nullptr;
   mCustomElementData = nullptr;
   mClassList = nullptr;
 }
@@ -1827,7 +1831,8 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INTERNAL(FragmentOrElement)
     }
 
     nsAutoString classes;
-    const nsAttrValue* classAttrValue = tmp->GetClasses();
+    const nsAttrValue* classAttrValue = tmp->IsElement() ?
+      tmp->AsElement()->GetClasses() : nullptr;
     if (classAttrValue) {
       classes.AppendLiteral(" class='");
       nsAutoString classString;
diff --git a/dom/base/FragmentOrElement.h b/dom/base/FragmentOrElement.h
index 3cb5575fe..1cd8033bb 100644
--- a/dom/base/FragmentOrElement.h
+++ b/dom/base/FragmentOrElement.h
@@ -24,6 +24,7 @@
 
 class ContentUnbinder;
 class nsContentList;
+class nsLabelsNodeList;
 class nsDOMAttributeMap;
 class nsDOMTokenList;
 class nsIControllers;
@@ -313,6 +314,11 @@ public:
      */
     RefPtr<nsDOMTokenList> mClassList;
 
+    /*
+     * An object implementing the .labels property for this element.
+     */
+    RefPtr<nsLabelsNodeList> mLabelsList;
+
     /**
      * ShadowRoot bound to the element.
      */
diff --git a/dom/base/nsContentList.cpp b/dom/base/nsContentList.cpp
index 09e949009..43e65777d 100644
--- a/dom/base/nsContentList.cpp
+++ b/dom/base/nsContentList.cpp
@@ -254,19 +254,6 @@ const nsCacheableFuncStringContentList::ContentListType
   nsCacheableFuncStringHTMLCollection::sType = nsCacheableFuncStringContentList::eHTMLCollection;
 #endif
 
-JSObject*
-nsCacheableFuncStringNodeList::WrapObject(JSContext *cx, JS::Handle<JSObject*> aGivenProto)
-{
-  return NodeListBinding::Wrap(cx, this, aGivenProto);
-}
-
-
-JSObject*
-nsCacheableFuncStringHTMLCollection::WrapObject(JSContext *cx, JS::Handle<JSObject*> aGivenProto)
-{
-  return HTMLCollectionBinding::Wrap(cx, this, aGivenProto);
-}
-
 // Hashtable for storing nsCacheableFuncStringContentList
 static PLDHashTable* gFuncStringContentListHashTable;
 
@@ -379,6 +366,7 @@ NS_GetFuncStringHTMLCollection(nsINode* aRootNode,
                                                                        aString);
 }
 
+//-----------------------------------------------------
 // nsContentList implementation
 
 nsContentList::nsContentList(nsINode* aRootNode,
@@ -660,7 +648,7 @@ nsContentList::AttributeChanged(nsIDocument *aDocument, Element* aElement,
                                 const nsAttrValue* aOldValue)
 {
   NS_PRECONDITION(aElement, "Must have a content node to work with");
-  
+
   if (!mFunc || !mFuncMayDependOnAttr || mState == LIST_DIRTY ||
       !MayContainRelevantNodes(aElement->GetParentNode()) ||
       !nsContentUtils::IsInSameAnonymousTree(mRootNode, aElement)) {
@@ -806,7 +794,7 @@ nsContentList::ContentInserted(nsIDocument *aDocument,
 
   ASSERT_IN_SYNC;
 }
- 
+
 void
 nsContentList::ContentRemoved(nsIDocument *aDocument,
                               nsIContent* aContainer,
@@ -1075,3 +1063,128 @@ nsContentList::AssertInSync()
   NS_ASSERTION(cnt == mElements.Length(), "Too few elements");
 }
 #endif
+
+//-----------------------------------------------------
+// nsCacheableFuncStringNodeList
+
+JSObject*
+nsCacheableFuncStringNodeList::WrapObject(JSContext *cx, JS::Handle<JSObject*> aGivenProto)
+{
+  return NodeListBinding::Wrap(cx, this, aGivenProto);
+}
+
+//-----------------------------------------------------
+// nsCacheableFuncStringHTMLCollection
+
+JSObject*
+nsCacheableFuncStringHTMLCollection::WrapObject(JSContext *cx, JS::Handle<JSObject*> aGivenProto)
+{
+  return HTMLCollectionBinding::Wrap(cx, this, aGivenProto);
+}
+
+//-----------------------------------------------------
+// nsLabelsNodeList
+
+JSObject*
+nsLabelsNodeList::WrapObject(JSContext *cx, JS::Handle<JSObject*> aGivenProto)
+{
+  return NodeListBinding::Wrap(cx, this, aGivenProto);
+}
+
+void
+nsLabelsNodeList::AttributeChanged(nsIDocument* aDocument, Element* aElement,
+                                   int32_t aNameSpaceID, nsIAtom* aAttribute,
+                                   int32_t aModType,
+                                   const nsAttrValue* aOldValue)
+{
+  MOZ_ASSERT(aElement, "Must have a content node to work with");
+  if (mState == LIST_DIRTY ||
+      !nsContentUtils::IsInSameAnonymousTree(mRootNode, aElement)) {
+    return;
+  }
+
+  // We need to handle input type changes to or from "hidden".
+  if (aElement->IsHTMLElement(nsGkAtoms::input) &&
+      aAttribute == nsGkAtoms::type && aNameSpaceID == kNameSpaceID_None) {
+    SetDirty();
+    return;
+  }
+}
+
+void
+nsLabelsNodeList::ContentAppended(nsIDocument* aDocument,
+                                  nsIContent* aContainer,
+                                  nsIContent* aFirstNewContent,
+                                  int32_t aNewIndexInContainer)
+{
+  // If a labelable element is moved to outside or inside of
+  // nested associated labels, we're gonna have to modify
+  // the content list.
+  if (mState != LIST_DIRTY ||
+      nsContentUtils::IsInSameAnonymousTree(mRootNode, aContainer)) {
+    SetDirty();
+    return;
+  }
+}
+
+void
+nsLabelsNodeList::ContentInserted(nsIDocument* aDocument,
+                                  nsIContent* aContainer,
+                                  nsIContent* aChild,
+                                  int32_t aIndexInContainer)
+{
+  // If a labelable element is moved to outside or inside of
+  // nested associated labels, we're gonna have to modify
+  // the content list.
+  if (mState != LIST_DIRTY ||
+      nsContentUtils::IsInSameAnonymousTree(mRootNode, aChild)) {
+    SetDirty();
+    return;
+  }
+}
+
+void
+nsLabelsNodeList::ContentRemoved(nsIDocument* aDocument,
+                                 nsIContent* aContainer,
+                                 nsIContent* aChild,
+                                 int32_t aIndexInContainer,
+                                 nsIContent* aPreviousSibling)
+{
+  // If a labelable element is removed, we're gonna have to clean
+  // the content list.
+  if (mState != LIST_DIRTY ||
+      nsContentUtils::IsInSameAnonymousTree(mRootNode, aChild)) {
+    SetDirty();
+    return;
+  }
+}
+
+void
+nsLabelsNodeList::MaybeResetRoot(nsINode* aRootNode)
+{
+  MOZ_ASSERT(aRootNode, "Must have root");
+  if (mRootNode == aRootNode) {
+    return;
+  }
+
+  if (mRootNode) {
+    mRootNode->RemoveMutationObserver(this);
+  }
+  mRootNode = aRootNode;
+  mRootNode->AddMutationObserver(this);
+  SetDirty();
+}
+
+void
+nsLabelsNodeList::PopulateSelf(uint32_t aNeededLength)
+{
+  MOZ_ASSERT(mRootNode, "Must have root");
+
+  // Start searching at the root.
+  nsINode* cur = mRootNode;
+  if (mElements.IsEmpty() && cur->IsElement() && Match(cur->AsElement())) {
+    mElements.AppendElement(cur->AsElement());
+  }
+
+  nsContentList::PopulateSelf(aNeededLength);
+}
diff --git a/dom/base/nsContentList.h b/dom/base/nsContentList.h
index 3878074b2..83d27da95 100644
--- a/dom/base/nsContentList.h
+++ b/dom/base/nsContentList.h
@@ -371,9 +371,9 @@ protected:
    * traversed the whole document (or both).
    *
    * @param aNeededLength the length the list should have when we are
-   *        done (unless it exhausts the document)   
+   *        done (unless it exhausts the document)
    */
-  void PopulateSelf(uint32_t aNeededLength);
+  virtual void PopulateSelf(uint32_t aNeededLength);
 
   /**
    * @param  aContainer a content node which must be a descendant of
@@ -584,4 +584,40 @@ public:
 #endif
 };
 
+class nsLabelsNodeList final : public nsContentList
+{
+public:
+  nsLabelsNodeList(nsINode* aRootNode,
+                   nsContentListMatchFunc aFunc,
+                   nsContentListDestroyFunc aDestroyFunc,
+                   void* aData)
+    : nsContentList(aRootNode, aFunc, aDestroyFunc, aData)
+  {
+  }
+
+  NS_DECL_NSIMUTATIONOBSERVER_ATTRIBUTECHANGED
+  NS_DECL_NSIMUTATIONOBSERVER_CONTENTAPPENDED
+  NS_DECL_NSIMUTATIONOBSERVER_CONTENTINSERTED
+  NS_DECL_NSIMUTATIONOBSERVER_CONTENTREMOVED
+
+  virtual JSObject* WrapObject(JSContext *cx, JS::Handle<JSObject*> aGivenProto) override;
+
+ /**
+  * Reset root, mutation observer, and clear content list
+  * if the root has been changed.
+  *
+  * @param aRootNode The node under which to limit our search.
+  */
+  void MaybeResetRoot(nsINode* aRootNode);
+
+private:
+ /**
+  * Start searching at the last one if we already have nodes, otherwise
+  * start searching at the root.
+  *
+  * @param aNeededLength The list of length should have when we are
+  *                      done (unless it exhausts the document).
+  */
+  void PopulateSelf(uint32_t aNeededLength) override;
+};
 #endif // nsContentList_h___
diff --git a/dom/base/nsContentListDeclarations.h b/dom/base/nsContentListDeclarations.h
index db3a09036..a5e0e3691 100644
--- a/dom/base/nsContentListDeclarations.h
+++ b/dom/base/nsContentListDeclarations.h
@@ -18,6 +18,12 @@ class nsINode;
 class nsString;
 class nsAString;
 
+namespace mozilla {
+namespace dom {
+class Element;
+} // namespace dom
+} // namespace mozilla
+
 // Magic namespace id that means "match all namespaces".  This is
 // negative so it won't collide with actual namespace constants.
 #define kNameSpaceID_Wildcard INT32_MIN
@@ -26,7 +32,7 @@ class nsAString;
 // arbitrary matching algorithm.  aContent is the content that may
 // match the list, while aNamespaceID, aAtom, and aData are whatever
 // was passed to the list's constructor.
-typedef bool (*nsContentListMatchFunc)(nsIContent* aContent,
+typedef bool (*nsContentListMatchFunc)(mozilla::dom::Element* aElement,
                                        int32_t aNamespaceID,
                                        nsIAtom* aAtom,
                                        void* aData);
diff --git a/dom/base/nsContentUtils.cpp b/dom/base/nsContentUtils.cpp
index 1cc352685..02c6bf1de 100644
--- a/dom/base/nsContentUtils.cpp
+++ b/dom/base/nsContentUtils.cpp
@@ -6287,11 +6287,11 @@ struct ClassMatchingInfo {
 
 // static
 bool
-nsContentUtils::MatchClassNames(nsIContent* aContent, int32_t aNamespaceID,
+nsContentUtils::MatchClassNames(Element* aElement, int32_t aNamespaceID,
                                 nsIAtom* aAtom, void* aData)
 {
   // We can't match if there are no class names
-  const nsAttrValue* classAttr = aContent->GetClasses();
+  const nsAttrValue* classAttr = aElement->GetClasses();
   if (!classAttr) {
     return false;
   }
diff --git a/dom/base/nsContentUtils.h b/dom/base/nsContentUtils.h
index f688eeecf..0a293d73e 100644
--- a/dom/base/nsContentUtils.h
+++ b/dom/base/nsContentUtils.h
@@ -2753,7 +2753,8 @@ private:
 
   static void DropFragmentParsers();
 
-  static bool MatchClassNames(nsIContent* aContent, int32_t aNamespaceID,
+  static bool MatchClassNames(mozilla::dom::Element* aElement,
+                              int32_t aNamespaceID,
                               nsIAtom* aAtom, void* aData);
   static void DestroyClassNameArray(void* aData);
   static void* AllocClassMatchingInfo(nsINode* aRootNode,
diff --git a/dom/base/nsGkAtomList.h b/dom/base/nsGkAtomList.h
index 0b76b2bea..e4ae7ede8 100644
--- a/dom/base/nsGkAtomList.h
+++ b/dom/base/nsGkAtomList.h
@@ -526,6 +526,7 @@ GK_ATOM(keytext, "keytext")
 GK_ATOM(keyup, "keyup")
 GK_ATOM(kind, "kind")
 GK_ATOM(label, "label")
+GK_ATOM(labels, "labels")
 GK_ATOM(lang, "lang")
 GK_ATOM(language, "language")
 GK_ATOM(last, "last")
@@ -950,6 +951,7 @@ GK_ATOM(onupdateready, "onupdateready")
 GK_ATOM(onupgradeneeded, "onupgradeneeded")
 GK_ATOM(onussdreceived, "onussdreceived")
 GK_ATOM(onversionchange, "onversionchange")
+GK_ATOM(onvisibilitychange, "onvisibilitychange")
 GK_ATOM(onvoicechange, "onvoicechange")
 GK_ATOM(onvoiceschanged, "onvoiceschanged")
 GK_ATOM(onvrdisplayconnect, "onvrdisplayconnect")
@@ -1449,6 +1451,7 @@ GK_ATOM(font_style, "font-style")
 GK_ATOM(font_variant, "font-variant")
 GK_ATOM(foreignObject, "foreignObject")
 GK_ATOM(fractalNoise, "fractalNoise")
+GK_ATOM(fr, "fr")
 GK_ATOM(fx, "fx")
 GK_ATOM(fy, "fy")
 GK_ATOM(G, "G")
diff --git a/dom/base/nsIContent.h b/dom/base/nsIContent.h
index f05c47a61..405090865 100644
--- a/dom/base/nsIContent.h
+++ b/dom/base/nsIContent.h
@@ -862,18 +862,6 @@ public:
   }
 
   /**
-   * Get the class list of this content node (this corresponds to the
-   * value of the class attribute).  This may be null if there are no
-   * classes, but that's not guaranteed.
-   */
-  const nsAttrValue* GetClasses() const {
-    if (HasFlag(NODE_MAY_HAVE_CLASS)) {
-      return DoGetClasses();
-    }
-    return nullptr;
-  }
-
-  /**
    * Walk aRuleWalker over the content style rules (presentational
    * hint rules) for this content node.
    */
@@ -990,13 +978,6 @@ protected:
    */
   nsIAtom* DoGetID() const;
 
-private:
-  /**
-   * Hook for implementing GetClasses.  This is guaranteed to only be
-   * called if the NODE_MAY_HAVE_CLASS flag is set.
-   */
-  const nsAttrValue* DoGetClasses() const;
-
 public:
 #ifdef DEBUG
   /**
diff --git a/dom/base/test/test_bug1375050.html b/dom/base/test/test_bug1375050.html
new file mode 100644
index 000000000..b91b859d0
--- /dev/null
+++ b/dom/base/test/test_bug1375050.html
@@ -0,0 +1,33 @@
+<!DOCTYPE HTML>

+<html>

+<!--

+https://bugzilla.mozilla.org/show_bug.cgi?id=1375050

+-->

+<head>

+  <meta charset="utf-8">

+  <title>Test for Bug 1375050</title>

+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>

+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>

+  <script type="application/javascript">

+      try { o1 = document.createElement('input');  } catch(e) { console.log(e); };

+      try { o2 = document.createElement('col');  } catch(e) { console.log(e); };

+      try { o4 = document.createRange(); } catch(e) { console.log(e); };

+      try { document.documentElement.appendChild(o1); } catch(e) { console.log(e); };

+      try { for (let p in o1) { let x = o1[p] }; } catch(e) { console.log(e); };

+      try { o4.selectNode(o1); } catch(e) { console.log(e); };

+      try { o6 = document.createComment(" x"); } catch(e) { console.log(e); }

+      try { o4.surroundContents(o6); } catch(e) { console.log(e); }

+      try { o7 = document.implementation.createDocument('', '', null).adoptNode(o1); } catch(e) {  console.log(e);};

+      try { o2.appendChild(o1); } catch(e) { console.log(e); };

+      ok(true, "Didn't crash.");

+  </script>

+</head>

+<body>

+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1375050">Mozilla Bug 1375050</a>

+<p id="display"></p>

+<div id="content" style="display: none">

+</div>

+<pre id="test">

+</pre>

+</body>

+</html>

diff --git a/dom/events/EventNameList.h b/dom/events/EventNameList.h
index b1be6dd76..ba2427623 100644
--- a/dom/events/EventNameList.h
+++ b/dom/events/EventNameList.h
@@ -674,6 +674,10 @@ DOCUMENT_ONLY_EVENT(selectionchange,
                     eSelectionChange,
                     EventNameType_HTMLXUL,
                     eBasicEventClass)
+DOCUMENT_ONLY_EVENT(visibilitychange,
+                    eVisibilityChange,
+                    EventNameType_HTMLXUL,
+                    eBasicEventClass)
 
 NON_IDL_EVENT(MozMouseHittest,
               eMouseHitTest,
diff --git a/dom/html/HTMLAllCollection.cpp b/dom/html/HTMLAllCollection.cpp
index afa160e0c..6305cce31 100644
--- a/dom/html/HTMLAllCollection.cpp
+++ b/dom/html/HTMLAllCollection.cpp
@@ -8,6 +8,7 @@
 
 #include "mozilla/dom/HTMLAllCollectionBinding.h"
 #include "mozilla/dom/Nullable.h"
+#include "mozilla/dom/Element.h"
 #include "nsHTMLDocument.h"
 
 namespace mozilla {
@@ -86,14 +87,14 @@ IsAllNamedElement(nsIContent* aContent)
 }
 
 static bool
-DocAllResultMatch(nsIContent* aContent, int32_t aNamespaceID, nsIAtom* aAtom,
+DocAllResultMatch(Element* aElement, int32_t aNamespaceID, nsIAtom* aAtom,
                   void* aData)
 {
-  if (aContent->GetID() == aAtom) {
+  if (aElement->GetID() == aAtom) {
     return true;
   }
 
-  nsGenericHTMLElement* elm = nsGenericHTMLElement::FromContent(aContent);
+  nsGenericHTMLElement* elm = nsGenericHTMLElement::FromContent(aElement);
   if (!elm) {
     return false;
   }
diff --git a/dom/html/HTMLDataListElement.cpp b/dom/html/HTMLDataListElement.cpp
index d9ad4da09..5aa772645 100644
--- a/dom/html/HTMLDataListElement.cpp
+++ b/dom/html/HTMLDataListElement.cpp
@@ -35,11 +35,11 @@ NS_INTERFACE_MAP_END_INHERITING(nsGenericHTMLElement)
 NS_IMPL_ELEMENT_CLONE(HTMLDataListElement)
 
 bool
-HTMLDataListElement::MatchOptions(nsIContent* aContent, int32_t aNamespaceID,
+HTMLDataListElement::MatchOptions(Element* aElement, int32_t aNamespaceID,
                                   nsIAtom* aAtom, void* aData)
 {
-  return aContent->NodeInfo()->Equals(nsGkAtoms::option, kNameSpaceID_XHTML) &&
-         !aContent->HasAttr(kNameSpaceID_None, nsGkAtoms::disabled);
+  return aElement->NodeInfo()->Equals(nsGkAtoms::option, kNameSpaceID_XHTML) &&
+         !aElement->HasAttr(kNameSpaceID_None, nsGkAtoms::disabled);
 }
 
 } // namespace dom
diff --git a/dom/html/HTMLDataListElement.h b/dom/html/HTMLDataListElement.h
index e0aff818b..ba2a2e0b4 100644
--- a/dom/html/HTMLDataListElement.h
+++ b/dom/html/HTMLDataListElement.h
@@ -37,8 +37,8 @@ public:
   virtual nsresult Clone(mozilla::dom::NodeInfo *aNodeInfo, nsINode **aResult) const override;
 
   // This function is used to generate the nsContentList (option elements).
-  static bool MatchOptions(nsIContent* aContent, int32_t aNamespaceID,
-                             nsIAtom* aAtom, void* aData);
+  static bool MatchOptions(Element* aElement, int32_t aNamespaceID,
+                           nsIAtom* aAtom, void* aData);
 
   NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(HTMLDataListElement,
                                            nsGenericHTMLElement)
diff --git a/dom/html/HTMLFieldSetElement.cpp b/dom/html/HTMLFieldSetElement.cpp
index 865d3c9cf..d72fd1061 100644
--- a/dom/html/HTMLFieldSetElement.cpp
+++ b/dom/html/HTMLFieldSetElement.cpp
@@ -120,10 +120,10 @@ HTMLFieldSetElement::GetType(nsAString& aType)
 
 /* static */
 bool
-HTMLFieldSetElement::MatchListedElements(nsIContent* aContent, int32_t aNamespaceID,
+HTMLFieldSetElement::MatchListedElements(Element* aElement, int32_t aNamespaceID,
                                          nsIAtom* aAtom, void* aData)
 {
-  nsCOMPtr<nsIFormControl> formControl = do_QueryInterface(aContent);
+  nsCOMPtr<nsIFormControl> formControl = do_QueryInterface(aElement);
   return formControl;
 }
 
diff --git a/dom/html/HTMLFieldSetElement.h b/dom/html/HTMLFieldSetElement.h
index d169434ae..96fff4582 100644
--- a/dom/html/HTMLFieldSetElement.h
+++ b/dom/html/HTMLFieldSetElement.h
@@ -124,8 +124,8 @@ private:
   void NotifyElementsForFirstLegendChange(bool aNotify);
 
   // This function is used to generate the nsContentList (listed form elements).
-  static bool MatchListedElements(nsIContent* aContent, int32_t aNamespaceID,
-                                    nsIAtom* aAtom, void* aData);
+  static bool MatchListedElements(Element* aElement, int32_t aNamespaceID,
+                                  nsIAtom* aAtom, void* aData);
 
   // listed form controls elements.
   RefPtr<nsContentList> mElements;
diff --git a/dom/html/HTMLInputElement.cpp b/dom/html/HTMLInputElement.cpp
index 78f74ae0c..d46eccdbc 100644
--- a/dom/html/HTMLInputElement.cpp
+++ b/dom/html/HTMLInputElement.cpp
@@ -8800,6 +8800,16 @@ HTMLInputElement::GetWebkitEntries(nsTArray<RefPtr<FileSystemEntry>>& aSequence)
   aSequence.AppendElements(mEntries);
 }
 
+already_AddRefed<nsINodeList>
+HTMLInputElement::GetLabels()
+{
+  if (!IsLabelable()) {
+    return nullptr;
+  }
+
+  return nsGenericHTMLElement::Labels();
+}
+
 } // namespace dom
 } // namespace mozilla
 
diff --git a/dom/html/HTMLInputElement.h b/dom/html/HTMLInputElement.h
index e5d670e08..9ca876aee 100644
--- a/dom/html/HTMLInputElement.h
+++ b/dom/html/HTMLInputElement.h
@@ -704,6 +704,8 @@ public:
 
   // XPCOM GetCustomVisibility() is OK
 
+  already_AddRefed<nsINodeList> GetLabels();
+
   // XPCOM Select() is OK
 
   Nullable<int32_t> GetSelectionStart(ErrorResult& aRv);
diff --git a/dom/html/HTMLLabelElement.cpp b/dom/html/HTMLLabelElement.cpp
index c1d22b0a6..d1c037336 100644
--- a/dom/html/HTMLLabelElement.cpp
+++ b/dom/html/HTMLLabelElement.cpp
@@ -14,6 +14,7 @@
 #include "nsFocusManager.h"
 #include "nsIDOMMouseEvent.h"
 #include "nsQueryObject.h"
+#include "mozilla/dom/ShadowRoot.h"
 
 // construction, destruction
 
@@ -268,17 +269,23 @@ HTMLLabelElement::GetLabeledElement() const
     return GetFirstLabelableDescendant();
   }
 
-  // We have a @for. The id has to be linked to an element in the same document
+  // We have a @for. The id has to be linked to an element in the same tree
   // and this element should be a labelable form control.
-  //XXXsmaug It is unclear how this should work in case the element is in
-  //         Shadow DOM.
-  //         See https://www.w3.org/Bugs/Public/show_bug.cgi?id=26365.
-  nsIDocument* doc = GetUncomposedDoc();
-  if (!doc) {
-    return nullptr;
+  nsINode* root = SubtreeRoot();
+  ShadowRoot* shadow = ShadowRoot::FromNode(root);
+  Element* element = nullptr;
+
+  if (shadow) {
+    element = shadow->GetElementById(elementId);
+  } else {
+    nsIDocument* doc = GetUncomposedDoc();
+    if (doc) {
+      element = doc->GetElementById(elementId);
+    } else {
+      element = nsContentUtils::MatchElementId(root->AsContent(), elementId);
+    }
   }
 
-  Element* element = doc->GetElementById(elementId);
   if (element && element->IsLabelable()) {
     return static_cast<nsGenericHTMLElement*>(element);
   }
diff --git a/dom/html/HTMLSelectElement.cpp b/dom/html/HTMLSelectElement.cpp
index 24ddabb65..53f42317a 100644
--- a/dom/html/HTMLSelectElement.cpp
+++ b/dom/html/HTMLSelectElement.cpp
@@ -735,12 +735,12 @@ HTMLSelectElement::SetLength(uint32_t aLength, ErrorResult& aRv)
 
 /* static */
 bool
-HTMLSelectElement::MatchSelectedOptions(nsIContent* aContent,
+HTMLSelectElement::MatchSelectedOptions(Element* aElement,
                                         int32_t /* unused */,
                                         nsIAtom* /* unused */,
                                         void* /* unused*/)
 {
-  HTMLOptionElement* option = HTMLOptionElement::FromContent(aContent);
+  HTMLOptionElement* option = HTMLOptionElement::FromContent(aElement);
   return option && option->Selected();
 }
 
diff --git a/dom/html/HTMLSelectElement.h b/dom/html/HTMLSelectElement.h
index d7e4350b4..8a25385de 100644
--- a/dom/html/HTMLSelectElement.h
+++ b/dom/html/HTMLSelectElement.h
@@ -247,7 +247,7 @@ public:
     mOptions->IndexedSetter(aIndex, aOption, aRv);
   }
 
-  static bool MatchSelectedOptions(nsIContent* aContent, int32_t, nsIAtom*,
+  static bool MatchSelectedOptions(Element* aElement, int32_t, nsIAtom*,
                                    void*);
 
   nsIHTMLCollection* SelectedOptions();
diff --git a/dom/html/HTMLTableRowElement.cpp b/dom/html/HTMLTableRowElement.cpp
index 2dec9c883..ac2463400 100644
--- a/dom/html/HTMLTableRowElement.cpp
+++ b/dom/html/HTMLTableRowElement.cpp
@@ -120,10 +120,10 @@ HTMLTableRowElement::SectionRowIndex() const
 }
 
 static bool
-IsCell(nsIContent *aContent, int32_t aNamespaceID,
+IsCell(Element *aElement, int32_t aNamespaceID,
        nsIAtom* aAtom, void *aData)
 {
-  return aContent->IsAnyOfHTMLElements(nsGkAtoms::td, nsGkAtoms::th);
+  return aElement->IsAnyOfHTMLElements(nsGkAtoms::td, nsGkAtoms::th);
 }
 
 nsIHTMLCollection*
diff --git a/dom/html/nsGenericHTMLElement.cpp b/dom/html/nsGenericHTMLElement.cpp
index d75001a83..2f890325a 100644
--- a/dom/html/nsGenericHTMLElement.cpp
+++ b/dom/html/nsGenericHTMLElement.cpp
@@ -108,6 +108,7 @@
 #include "mozilla/StyleSetHandle.h"
 #include "mozilla/StyleSetHandleInlines.h"
 #include "ReferrerPolicy.h"
+#include "mozilla/dom/HTMLLabelElement.h"
 
 using namespace mozilla;
 using namespace mozilla::dom;
@@ -493,6 +494,14 @@ nsGenericHTMLElement::BindToTree(nsIDocument* aDocument, nsIContent* aParent,
     }
   }
 
+  // We need to consider a labels element is moved to another subtree
+  // with different root, it needs to update labels list and its root
+  // as well.
+  nsDOMSlots* slots = GetExistingDOMSlots();
+  if (slots && slots->mLabelsList) {
+    slots->mLabelsList->MaybeResetRoot(SubtreeRoot());
+  }
+
   return rv;
 }
 
@@ -513,6 +522,13 @@ nsGenericHTMLElement::UnbindFromTree(bool aDeep, bool aNullParent)
     }
   }
 
+  // We need to consider a labels element is removed from tree,
+  // it needs to update labels list and its root as well.
+  nsDOMSlots* slots = GetExistingDOMSlots();
+  if (slots && slots->mLabelsList) {
+    slots->mLabelsList->MaybeResetRoot(SubtreeRoot());
+  }
+
   nsStyledElement::UnbindFromTree(aDeep, aNullParent);
 }
 
@@ -1701,6 +1717,30 @@ nsGenericHTMLElement::IsLabelable() const
   return IsAnyOfHTMLElements(nsGkAtoms::progress, nsGkAtoms::meter);
 }
 
+/* static */ bool
+nsGenericHTMLElement::MatchLabelsElement(Element* aElement, int32_t aNamespaceID,
+                                         nsIAtom* aAtom, void* aData)
+{
+  HTMLLabelElement* element = HTMLLabelElement::FromContent(aElement);
+  return element && element->GetControl() == aData;
+}
+
+already_AddRefed<nsINodeList>
+nsGenericHTMLElement::Labels()
+{
+  MOZ_ASSERT(IsLabelable(),
+             "Labels() only allow labelable elements to use it.");
+  nsDOMSlots* slots = DOMSlots();
+
+  if (!slots->mLabelsList) {
+    slots->mLabelsList = new nsLabelsNodeList(SubtreeRoot(), MatchLabelsElement,
+                                              nullptr, this);
+  }
+
+  RefPtr<nsLabelsNodeList> labels = slots->mLabelsList;
+  return labels.forget();
+}
+
 bool
 nsGenericHTMLElement::IsInteractiveHTMLContent(bool aIgnoreTabindex) const
 {
diff --git a/dom/html/nsGenericHTMLElement.h b/dom/html/nsGenericHTMLElement.h
index 3cca41c3d..0635c27e1 100644
--- a/dom/html/nsGenericHTMLElement.h
+++ b/dom/html/nsGenericHTMLElement.h
@@ -834,6 +834,12 @@ public:
   }
 
   virtual bool IsLabelable() const override;
+
+  static bool MatchLabelsElement(Element* aElement, int32_t aNamespaceID,
+                                 nsIAtom* aAtom, void* aData);
+
+  already_AddRefed<nsINodeList> Labels();
+
   virtual bool IsInteractiveHTMLContent(bool aIgnoreTabindex) const override;
 
   static bool TouchEventsEnabled(JSContext* /* unused */, JSObject* /* unused */);
diff --git a/dom/html/nsHTMLDocument.cpp b/dom/html/nsHTMLDocument.cpp
index 7d66aab04..fea78dc37 100644
--- a/dom/html/nsHTMLDocument.cpp
+++ b/dom/html/nsHTMLDocument.cpp
@@ -1100,31 +1100,31 @@ nsHTMLDocument::Applets()
 }
 
 bool
-nsHTMLDocument::MatchLinks(nsIContent *aContent, int32_t aNamespaceID,
+nsHTMLDocument::MatchLinks(Element* aElement, int32_t aNamespaceID,
                            nsIAtom* aAtom, void* aData)
 {
-  nsIDocument* doc = aContent->GetUncomposedDoc();
+  nsIDocument* doc = aElement->GetUncomposedDoc();
 
   if (doc) {
-    NS_ASSERTION(aContent->IsInUncomposedDoc(),
+    NS_ASSERTION(aElement->IsInUncomposedDoc(),
                  "This method should never be called on content nodes that "
                  "are not in a document!");
 #ifdef DEBUG
     {
       nsCOMPtr<nsIHTMLDocument> htmldoc =
-        do_QueryInterface(aContent->GetUncomposedDoc());
+        do_QueryInterface(aElement->GetUncomposedDoc());
       NS_ASSERTION(htmldoc,
                    "Huh, how did this happen? This should only be used with "
                    "HTML documents!");
     }
 #endif
 
-    mozilla::dom::NodeInfo *ni = aContent->NodeInfo();
+    mozilla::dom::NodeInfo *ni = aElement->NodeInfo();
 
     nsIAtom *localName = ni->NameAtom();
     if (ni->NamespaceID() == kNameSpaceID_XHTML &&
         (localName == nsGkAtoms::a || localName == nsGkAtoms::area)) {
-      return aContent->HasAttr(kNameSpaceID_None, nsGkAtoms::href);
+      return aElement->HasAttr(kNameSpaceID_None, nsGkAtoms::href);
     }
   }
 
@@ -1148,24 +1148,24 @@ nsHTMLDocument::Links()
 }
 
 bool
-nsHTMLDocument::MatchAnchors(nsIContent *aContent, int32_t aNamespaceID,
+nsHTMLDocument::MatchAnchors(Element* aElement, int32_t aNamespaceID,
                              nsIAtom* aAtom, void* aData)
 {
-  NS_ASSERTION(aContent->IsInUncomposedDoc(),
+  NS_ASSERTION(aElement->IsInUncomposedDoc(),
                "This method should never be called on content nodes that "
                "are not in a document!");
 #ifdef DEBUG
   {
     nsCOMPtr<nsIHTMLDocument> htmldoc =
-      do_QueryInterface(aContent->GetUncomposedDoc());
+      do_QueryInterface(aElement->GetUncomposedDoc());
     NS_ASSERTION(htmldoc,
                  "Huh, how did this happen? This should only be used with "
                  "HTML documents!");
   }
 #endif
 
-  if (aContent->NodeInfo()->Equals(nsGkAtoms::a, kNameSpaceID_XHTML)) {
-    return aContent->HasAttr(kNameSpaceID_None, nsGkAtoms::name);
+  if (aElement->IsHTMLElement(nsGkAtoms::a)) {
+    return aElement->HasAttr(kNameSpaceID_None, nsGkAtoms::name);
   }
 
   return false;
@@ -1952,14 +1952,14 @@ nsHTMLDocument::Writeln(JSContext* cx, const Sequence<nsString>& aText,
 }
 
 bool
-nsHTMLDocument::MatchNameAttribute(nsIContent* aContent, int32_t aNamespaceID,
+nsHTMLDocument::MatchNameAttribute(Element* aElement, int32_t aNamespaceID,
                                    nsIAtom* aAtom, void* aData)
 {
-  NS_PRECONDITION(aContent, "Must have content node to work with!");
+  NS_PRECONDITION(aElement, "Must have element to work with!");
   nsString* elementName = static_cast<nsString*>(aData);
   return
-    aContent->GetNameSpaceID() == kNameSpaceID_XHTML &&
-    aContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::name,
+    aElement->GetNameSpaceID() == kNameSpaceID_XHTML &&
+    aElement->AttrValueIs(kNameSpaceID_None, nsGkAtoms::name,
                           *elementName, eCaseMatters);
 }
 
@@ -2279,10 +2279,10 @@ nsHTMLDocument::GetForms()
   return mForms;
 }
 
-static bool MatchFormControls(nsIContent* aContent, int32_t aNamespaceID,
-                                nsIAtom* aAtom, void* aData)
+static bool MatchFormControls(Element* aElement, int32_t aNamespaceID,
+                              nsIAtom* aAtom, void* aData)
 {
-  return aContent->IsNodeOfType(nsIContent::eHTML_FORM_CONTROL);
+  return aElement->IsNodeOfType(nsIContent::eHTML_FORM_CONTROL);
 }
 
 nsContentList*
diff --git a/dom/html/nsHTMLDocument.h b/dom/html/nsHTMLDocument.h
index 2dbbf2b57..426ebddc5 100644
--- a/dom/html/nsHTMLDocument.h
+++ b/dom/html/nsHTMLDocument.h
@@ -261,12 +261,13 @@ protected:
 
   nsIContent *MatchId(nsIContent *aContent, const nsAString& aId);
 
-  static bool MatchLinks(nsIContent *aContent, int32_t aNamespaceID,
+  static bool MatchLinks(mozilla::dom::Element* aElement, int32_t aNamespaceID,
+                         nsIAtom* aAtom, void* aData);
+  static bool MatchAnchors(mozilla::dom::Element* aElement, int32_t aNamespaceID,
                            nsIAtom* aAtom, void* aData);
-  static bool MatchAnchors(nsIContent *aContent, int32_t aNamespaceID,
-                             nsIAtom* aAtom, void* aData);
-  static bool MatchNameAttribute(nsIContent* aContent, int32_t aNamespaceID,
-                                   nsIAtom* aAtom, void* aData);
+  static bool MatchNameAttribute(mozilla::dom::Element* aElement,
+                                 int32_t aNamespaceID,
+                                 nsIAtom* aAtom, void* aData);
   static void* UseExistingNameString(nsINode* aRootNode, const nsString* aName);
 
   static void DocumentWriteTerminationFunc(nsISupports *aRef);
diff --git a/dom/html/test/forms/test_button_attributes_reflection.html b/dom/html/test/forms/test_button_attributes_reflection.html
index 26858e939..4e702b3ac 100644
--- a/dom/html/test/forms/test_button_attributes_reflection.html
+++ b/dom/html/test/forms/test_button_attributes_reflection.html
@@ -128,9 +128,12 @@ is(typeof(document.createElement("button").setCustomValidity), "function",
    "button.setCustomValidity should be a function");
 
 // .labels
-todo("labels" in document.createElement("button"),
-     "button.labels isn't implemented yet");
-
+ok("labels" in document.createElement("button"),
+   "button.labels should be an IDL attribute of the button element");
+is(typeof(document.createElement("button").labels), "object",
+   "button.labels should be an object");
+ok(document.createElement("button").labels instanceof NodeList,
+   "button.labels sohuld be an instance of NodeList");
 </script>
 </pre>
 </body>
diff --git a/dom/svg/SVGGradientElement.cpp b/dom/svg/SVGGradientElement.cpp
index 1bcac67e6..93767c934 100644
--- a/dom/svg/SVGGradientElement.cpp
+++ b/dom/svg/SVGGradientElement.cpp
@@ -198,13 +198,14 @@ SVGRadialGradientElement::WrapNode(JSContext* aCx, JS::Handle<JSObject*> aGivenP
   return SVGRadialGradientElementBinding::Wrap(aCx, this, aGivenProto);
 }
 
-nsSVGElement::LengthInfo SVGRadialGradientElement::sLengthInfo[5] =
+nsSVGElement::LengthInfo SVGRadialGradientElement::sLengthInfo[6] =
 {
   { &nsGkAtoms::cx, 50, nsIDOMSVGLength::SVG_LENGTHTYPE_PERCENTAGE, SVGContentUtils::X },
   { &nsGkAtoms::cy, 50, nsIDOMSVGLength::SVG_LENGTHTYPE_PERCENTAGE, SVGContentUtils::Y },
   { &nsGkAtoms::r, 50, nsIDOMSVGLength::SVG_LENGTHTYPE_PERCENTAGE, SVGContentUtils::XY },
   { &nsGkAtoms::fx, 50, nsIDOMSVGLength::SVG_LENGTHTYPE_PERCENTAGE, SVGContentUtils::X },
   { &nsGkAtoms::fy, 50, nsIDOMSVGLength::SVG_LENGTHTYPE_PERCENTAGE, SVGContentUtils::Y },
+  { &nsGkAtoms::fr, 0, nsIDOMSVGLength::SVG_LENGTHTYPE_PERCENTAGE, SVGContentUtils::XY },
 };
 
 //----------------------------------------------------------------------
@@ -252,6 +253,12 @@ SVGRadialGradientElement::Fy()
   return mLengthAttributes[ATTR_FY].ToDOMAnimatedLength(this);
 }
 
+already_AddRefed<SVGAnimatedLength>
+SVGRadialGradientElement::Fr()
+{
+  return mLengthAttributes[ATTR_FR].ToDOMAnimatedLength(this);
+}
+
 //----------------------------------------------------------------------
 // nsSVGElement methods
 
diff --git a/dom/svg/SVGGradientElement.h b/dom/svg/SVGGradientElement.h
index 7b2c6b220..ce9f3b4b1 100644
--- a/dom/svg/SVGGradientElement.h
+++ b/dom/svg/SVGGradientElement.h
@@ -139,13 +139,14 @@ public:
   already_AddRefed<SVGAnimatedLength> R();
   already_AddRefed<SVGAnimatedLength> Fx();
   already_AddRefed<SVGAnimatedLength> Fy();
+  already_AddRefed<SVGAnimatedLength> Fr();
 protected:
 
   virtual LengthAttributesInfo GetLengthInfo() override;
 
-  enum { ATTR_CX, ATTR_CY, ATTR_R, ATTR_FX, ATTR_FY };
-  nsSVGLength2 mLengthAttributes[5];
-  static LengthInfo sLengthInfo[5];
+  enum { ATTR_CX, ATTR_CY, ATTR_R, ATTR_FX, ATTR_FY, ATTR_FR };
+  nsSVGLength2 mLengthAttributes[6];
+  static LengthInfo sLengthInfo[6];
 };
 
 } // namespace dom
diff --git a/dom/webidl/Document.webidl b/dom/webidl/Document.webidl
index c895fad39..f05656e84 100644
--- a/dom/webidl/Document.webidl
+++ b/dom/webidl/Document.webidl
@@ -275,10 +275,11 @@ partial interface Document {
     object registerElement(DOMString name, optional ElementRegistrationOptions options);
 };
 
-// http://dvcs.w3.org/hg/webperf/raw-file/tip/specs/PageVisibility/Overview.html#sec-document-interface
+// https://w3c.github.io/page-visibility/#extensions-to-the-document-interface
 partial interface Document {
   readonly attribute boolean hidden;
   readonly attribute VisibilityState visibilityState;
+           attribute EventHandler onvisibilitychange;
 };
 
 // http://dev.w3.org/csswg/cssom/#extensions-to-the-document-interface
diff --git a/dom/webidl/HTMLButtonElement.webidl b/dom/webidl/HTMLButtonElement.webidl
index c50e09ae0..579efa39c 100644
--- a/dom/webidl/HTMLButtonElement.webidl
+++ b/dom/webidl/HTMLButtonElement.webidl
@@ -44,6 +44,5 @@ interface HTMLButtonElement : HTMLElement {
   boolean reportValidity();
   void setCustomValidity(DOMString error);
 
-// Not yet implemented:
-//  readonly attribute NodeList labels;
+  readonly attribute NodeList labels;
 };
diff --git a/dom/webidl/HTMLInputElement.webidl b/dom/webidl/HTMLInputElement.webidl
index d3d537f84..050d19510 100644
--- a/dom/webidl/HTMLInputElement.webidl
+++ b/dom/webidl/HTMLInputElement.webidl
@@ -111,7 +111,7 @@ interface HTMLInputElement : HTMLElement {
   boolean reportValidity();
   void setCustomValidity(DOMString error);
 
-  // Bug 850365 readonly attribute NodeList labels;
+  readonly attribute NodeList? labels;
 
   void select();
 
diff --git a/dom/webidl/HTMLMeterElement.webidl b/dom/webidl/HTMLMeterElement.webidl
index 1f80764e9..104e00353 100644
--- a/dom/webidl/HTMLMeterElement.webidl
+++ b/dom/webidl/HTMLMeterElement.webidl
@@ -26,8 +26,5 @@ interface HTMLMeterElement : HTMLElement {
            [SetterThrows]
            attribute double optimum;
 
-  /**
-   * The labels attribute will be done with bug 556743.
-   */
-  //readonly attribute NodeList labels;
+           readonly attribute NodeList labels;
 };
diff --git a/dom/webidl/HTMLOutputElement.webidl b/dom/webidl/HTMLOutputElement.webidl
index 05dcf1800..d0e4ecbe6 100644
--- a/dom/webidl/HTMLOutputElement.webidl
+++ b/dom/webidl/HTMLOutputElement.webidl
@@ -33,6 +33,5 @@ interface HTMLOutputElement : HTMLElement {
   boolean reportValidity();
   void setCustomValidity(DOMString error);
 
-// Not yet implemented (bug 556743).
-//  readonly attribute NodeList labels;
+  readonly attribute NodeList labels;
 };
diff --git a/dom/webidl/HTMLProgressElement.webidl b/dom/webidl/HTMLProgressElement.webidl
index 3d1000d22..028728e22 100644
--- a/dom/webidl/HTMLProgressElement.webidl
+++ b/dom/webidl/HTMLProgressElement.webidl
@@ -17,9 +17,5 @@ interface HTMLProgressElement : HTMLElement {
            [SetterThrows]
            attribute double max;
   readonly attribute double position;
-
-  /**
-   * The labels attribute will be done with bug 567740.
-   */
-  //readonly attribute NodeList labels;
+  readonly attribute NodeList labels;
 };
diff --git a/dom/webidl/HTMLSelectElement.webidl b/dom/webidl/HTMLSelectElement.webidl
index 74fc7b2cf..b18ca3634 100644
--- a/dom/webidl/HTMLSelectElement.webidl
+++ b/dom/webidl/HTMLSelectElement.webidl
@@ -53,7 +53,7 @@ interface HTMLSelectElement : HTMLElement {
   boolean reportValidity();
   void setCustomValidity(DOMString error);
 
-// NYI:  readonly attribute NodeList labels;
+  readonly attribute NodeList labels;
 
   // https://www.w3.org/Bugs/Public/show_bug.cgi?id=20720
   void remove();
diff --git a/dom/webidl/HTMLTextAreaElement.webidl b/dom/webidl/HTMLTextAreaElement.webidl
index b1005ed42..4df687a0b 100644
--- a/dom/webidl/HTMLTextAreaElement.webidl
+++ b/dom/webidl/HTMLTextAreaElement.webidl
@@ -57,7 +57,7 @@ interface HTMLTextAreaElement : HTMLElement {
   boolean reportValidity();
   void setCustomValidity(DOMString error);
 
-  // readonly attribute NodeList labels;
+  readonly attribute NodeList labels;
 
   void select();
   [Throws]
diff --git a/dom/webidl/SVGRadialGradientElement.webidl b/dom/webidl/SVGRadialGradientElement.webidl
index d4a3724f6..8d7ce9016 100644
--- a/dom/webidl/SVGRadialGradientElement.webidl
+++ b/dom/webidl/SVGRadialGradientElement.webidl
@@ -21,5 +21,7 @@ interface SVGRadialGradientElement : SVGGradientElement {
   readonly attribute SVGAnimatedLength fx;
   [Constant]
   readonly attribute SVGAnimatedLength fy;
-  // readonly attribute SVGAnimatedLength fr;
+  // XXX: Bug 1242048
+  // [SameObject]
+  readonly attribute SVGAnimatedLength fr;
 };
diff --git a/dom/workers/WorkerScope.cpp b/dom/workers/WorkerScope.cpp
index d9a987b62..54252e53b 100644
--- a/dom/workers/WorkerScope.cpp
+++ b/dom/workers/WorkerScope.cpp
@@ -968,11 +968,4 @@ IsDebuggerSandbox(JSObject* object)
     SimpleGlobalObject::GlobalType::WorkerDebuggerSandbox;
 }
 
-bool
-GetterOnlyJSNative(JSContext* aCx, unsigned aArgc, JS::Value* aVp)
-{
-  JS_ReportErrorNumberASCII(aCx, js::GetErrorMessage, nullptr, JSMSG_GETTER_ONLY);
-  return false;
-}
-
 END_WORKERS_NAMESPACE
diff --git a/dom/workers/Workers.h b/dom/workers/Workers.h
index ad083d3b8..cd15a4d7c 100644
--- a/dom/workers/Workers.h
+++ b/dom/workers/Workers.h
@@ -362,14 +362,6 @@ IsDebuggerGlobal(JSObject* global);
 bool
 IsDebuggerSandbox(JSObject* object);
 
-// Throws the JSMSG_GETTER_ONLY exception.  This shouldn't be used going
-// forward -- getter-only properties should just use JS_PSG for the setter
-// (implying no setter at all), which will not throw when set in non-strict
-// code but will in strict code.  Old code should use this only for temporary
-// compatibility reasons.
-extern bool
-GetterOnlyJSNative(JSContext* aCx, unsigned aArgc, JS::Value* aVp);
-
 END_WORKERS_NAMESPACE
 
 #endif // mozilla_dom_workers_workers_h__
diff --git a/dom/xul/XULDocument.cpp b/dom/xul/XULDocument.cpp
index ae3cdb7eb..1dcb55aee 100644
--- a/dom/xul/XULDocument.cpp
+++ b/dom/xul/XULDocument.cpp
@@ -1919,26 +1919,26 @@ XULDocument::StartLayout(void)
 
 /* static */
 bool
-XULDocument::MatchAttribute(nsIContent* aContent,
+XULDocument::MatchAttribute(Element* aElement,
                             int32_t aNamespaceID,
                             nsIAtom* aAttrName,
                             void* aData)
 {
-    NS_PRECONDITION(aContent, "Must have content node to work with!");
+    NS_PRECONDITION(aElement, "Must have content node to work with!");
     nsString* attrValue = static_cast<nsString*>(aData);
     if (aNamespaceID != kNameSpaceID_Unknown &&
         aNamespaceID != kNameSpaceID_Wildcard) {
         return attrValue->EqualsLiteral("*") ?
-            aContent->HasAttr(aNamespaceID, aAttrName) :
-            aContent->AttrValueIs(aNamespaceID, aAttrName, *attrValue,
+            aElement->HasAttr(aNamespaceID, aAttrName) :
+            aElement->AttrValueIs(aNamespaceID, aAttrName, *attrValue,
                                   eCaseMatters);
     }
 
     // Qualified name match. This takes more work.
 
-    uint32_t count = aContent->GetAttrCount();
+    uint32_t count = aElement->GetAttrCount();
     for (uint32_t i = 0; i < count; ++i) {
-        const nsAttrName* name = aContent->GetAttrNameAt(i);
+        const nsAttrName* name = aElement->GetAttrNameAt(i);
         bool nameMatch;
         if (name->IsAtom()) {
             nameMatch = name->Atom() == aAttrName;
@@ -1950,7 +1950,7 @@ XULDocument::MatchAttribute(nsIContent* aContent,
 
         if (nameMatch) {
             return attrValue->EqualsLiteral("*") ||
-                aContent->AttrValueIs(name->NamespaceID(), name->LocalName(),
+                aElement->AttrValueIs(name->NamespaceID(), name->LocalName(),
                                       *attrValue, eCaseMatters);
         }
     }
diff --git a/dom/xul/XULDocument.h b/dom/xul/XULDocument.h
index a2f82bb89..06abb797f 100644
--- a/dom/xul/XULDocument.h
+++ b/dom/xul/XULDocument.h
@@ -180,7 +180,7 @@ public:
     NS_IMETHOD OnScriptCompileComplete(JSScript* aScript, nsresult aStatus) override;
 
     static bool
-    MatchAttribute(nsIContent* aContent,
+    MatchAttribute(Element* aContent,
                    int32_t aNameSpaceID,
                    nsIAtom* aAttrName,
                    void* aData);
diff --git a/image/DrawResult.h b/image/DrawResult.h
index 8240ede26..912f59dc3 100644
--- a/image/DrawResult.h
+++ b/image/DrawResult.h
@@ -6,6 +6,7 @@
 #ifndef mozilla_image_DrawResult_h
 #define mozilla_image_DrawResult_h
 
+#include <cstdint> // for uint8_t
 #include "mozilla/Attributes.h"
 #include "mozilla/Likely.h"
 
diff --git a/js/src/js.msg b/js/src/js.msg
index 246e363c3..cb5fc383b 100644
--- a/js/src/js.msg
+++ b/js/src/js.msg
@@ -65,7 +65,7 @@ MSG_DEF(JSMSG_BAD_GETTER_OR_SETTER,    1, JSEXN_TYPEERR, "invalid {0} usage")
 MSG_DEF(JSMSG_BAD_ARRAY_LENGTH,        0, JSEXN_RANGEERR, "invalid array length")
 MSG_DEF(JSMSG_REDECLARED_VAR,          2, JSEXN_SYNTAXERR, "redeclaration of {0} {1}")
 MSG_DEF(JSMSG_UNDECLARED_VAR,          1, JSEXN_REFERENCEERR, "assignment to undeclared variable {0}")
-MSG_DEF(JSMSG_GETTER_ONLY,             0, JSEXN_TYPEERR, "setting a property that has only a getter")
+MSG_DEF(JSMSG_GETTER_ONLY,             1, JSEXN_TYPEERR, "setting getter-only property {0}")
 MSG_DEF(JSMSG_OVERWRITING_ACCESSOR,    1, JSEXN_TYPEERR, "can't overwrite accessor property {0}")
 MSG_DEF(JSMSG_UNDEFINED_PROP,          1, JSEXN_REFERENCEERR, "reference to undefined property {0}")
 MSG_DEF(JSMSG_INVALID_MAP_ITERABLE,    1, JSEXN_TYPEERR, "iterable for {0} should have array-like objects")
diff --git a/js/src/jsobj.cpp b/js/src/jsobj.cpp
index a39a4b0a0..33feb0a54 100644
--- a/js/src/jsobj.cpp
+++ b/js/src/jsobj.cpp
@@ -3298,18 +3298,6 @@ GetObjectSlotNameFunctor::operator()(JS::CallbackTracer* trc, char* buf, size_t
     }
 }
 
-bool
-js::ReportGetterOnlyAssignment(JSContext* cx, bool strict)
-{
-    return JS_ReportErrorFlagsAndNumberASCII(cx,
-                                             strict
-                                             ? JSREPORT_ERROR
-                                             : JSREPORT_WARNING | JSREPORT_STRICT,
-                                             GetErrorMessage, nullptr,
-                                             JSMSG_GETTER_ONLY);
-}
-
-
 /*** Debugging routines **************************************************************************/
 
 #ifdef DEBUG
diff --git a/js/src/jsobj.h b/js/src/jsobj.h
index fbf4e47be..af79131af 100644
--- a/js/src/jsobj.h
+++ b/js/src/jsobj.h
@@ -1320,9 +1320,6 @@ template<XDRMode mode>
 bool
 XDRObjectLiteral(XDRState<mode>* xdr, MutableHandleObject obj);
 
-extern bool
-ReportGetterOnlyAssignment(JSContext* cx, bool strict);
-
 /*
  * Report a TypeError: "so-and-so is not an object".
  * Using NotNullObject is usually less code.
diff --git a/layout/base/nsLayoutDebugger.cpp b/layout/base/nsLayoutDebugger.cpp
index 22c313c72..6ce629bc9 100644
--- a/layout/base/nsLayoutDebugger.cpp
+++ b/layout/base/nsLayoutDebugger.cpp
@@ -126,8 +126,10 @@ PrintDisplayItemTo(nsDisplayListBuilder* aBuilder, nsDisplayItem* aItem,
       contentData.AppendLiteral(" id:");
       contentData.Append(tmp);
     }
-    if (content->GetClasses()) {
-      content->GetClasses()->ToString(tmp);
+    const nsAttrValue* classes = content->IsElement() ?
+      content->AsElement()->GetClasses() : nullptr;
+    if (classes) {
+      classes->ToString(tmp);
       contentData.AppendLiteral(" class:");
       contentData.Append(tmp);
     }
diff --git a/layout/base/nsLayoutUtils.cpp b/layout/base/nsLayoutUtils.cpp
index 789c91f50..c8c91b251 100644
--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@@ -4637,6 +4637,63 @@ GetPercentBSize(const nsStyleCoord& aStyle,
   return true;
 }
 
+// Return true if aStyle can be resolved to a definite value and if so
+// return that value in aResult.
+static bool
+GetDefiniteSize(const nsStyleCoord&       aStyle,
+                nsIFrame*                 aFrame,
+                bool                      aIsInlineAxis,
+                const Maybe<LogicalSize>& aPercentageBasis,
+                nscoord*                  aResult)
+{
+  switch (aStyle.GetUnit()) {
+    case eStyleUnit_Coord:
+      *aResult = aStyle.GetCoordValue();
+      return true;
+    case eStyleUnit_Percent: {
+      if (aPercentageBasis.isNothing()) {
+        return false;
+      }
+      auto wm = aFrame->GetWritingMode();
+      nscoord pb = aIsInlineAxis ? aPercentageBasis.value().ISize(wm)
+                                 : aPercentageBasis.value().BSize(wm);
+      if (pb != NS_UNCONSTRAINEDSIZE) {
+        nscoord p = NSToCoordFloorClamped(pb * aStyle.GetPercentValue());
+        *aResult = std::max(nscoord(0), p);
+        return true;
+      }
+      return false;
+    }
+    case eStyleUnit_Calc: {
+      nsStyleCoord::Calc* calc = aStyle.GetCalcValue();
+      if (calc->mPercent != 0.0f) {
+        if (aPercentageBasis.isNothing()) {
+          return false;
+        }
+        auto wm = aFrame->GetWritingMode();
+        nscoord pb = aIsInlineAxis ? aPercentageBasis.value().ISize(wm)
+                                   : aPercentageBasis.value().BSize(wm);
+        if (pb == NS_UNCONSTRAINEDSIZE) {
+          // XXXmats given that we're calculating an intrinsic size here,
+          // maybe we should back-compute the calc-size using AddPercents?
+          return false;
+        }
+        *aResult = std::max(0, calc->mLength +
+                               NSToCoordFloorClamped(pb * calc->mPercent));
+      } else {
+        *aResult = std::max(0, calc->mLength);
+      }
+      return true;
+    }
+    default:
+      return false;
+  }
+}
+
+//
+// NOTE: this function will be replaced by GetDefiniteSizeTakenByBoxSizing (bug 1363918).
+// Please do not add new uses of this function.
+//
 // Get the amount of vertical space taken out of aFrame's content area due to
 // its borders and paddings given the box-sizing value in aBoxSizing.  We don't
 // get aBoxSizing from the frame because some callers want to compute this for
@@ -4681,6 +4738,54 @@ GetBSizeTakenByBoxSizing(StyleBoxSizing aBoxSizing,
   return bSizeTakenByBoxSizing;
 }
 
+// Get the amount of space taken out of aFrame's content area due to its
+// borders and paddings given the box-sizing value in aBoxSizing.  We don't
+// get aBoxSizing from the frame because some callers want to compute this for
+// specific box-sizing values.
+// aIsInlineAxis is true if we're computing for aFrame's inline axis.
+// aIgnorePadding is true if padding should be ignored.
+static nscoord
+GetDefiniteSizeTakenByBoxSizing(StyleBoxSizing aBoxSizing,
+                                nsIFrame* aFrame,
+                                bool aIsInlineAxis,
+                                bool aIgnorePadding,
+                                const Maybe<LogicalSize>& aPercentageBasis)
+{
+  nscoord sizeTakenByBoxSizing = 0;
+  if (MOZ_UNLIKELY(aBoxSizing == StyleBoxSizing::Border)) {
+    const bool isHorizontalAxis =
+      aIsInlineAxis == !aFrame->GetWritingMode().IsVertical();
+    const nsStyleBorder* styleBorder = aFrame->StyleBorder();
+    sizeTakenByBoxSizing =
+      isHorizontalAxis ? styleBorder->GetComputedBorder().LeftRight()
+                       : styleBorder->GetComputedBorder().TopBottom();
+    if (!aIgnorePadding) {
+      const nsStyleSides& stylePadding = aFrame->StylePadding()->mPadding;
+      const nsStyleCoord& pStart =
+        stylePadding.Get(isHorizontalAxis ? eSideLeft : eSideTop);
+      const nsStyleCoord& pEnd =
+        stylePadding.Get(isHorizontalAxis ? eSideRight : eSideBottom);
+      nscoord pad;
+      // XXXbz Calling GetPercentBSize on padding values looks bogus, since
+      // percent padding is always a percentage of the inline-size of the
+      // containing block.  We should perhaps just treat non-absolute paddings
+      // here as 0 instead, except that in some cases the width may in fact be
+      // known.  See bug 1231059.
+      if (GetDefiniteSize(pStart, aFrame, aIsInlineAxis, aPercentageBasis, &pad) ||
+          (aPercentageBasis.isNothing() &&
+           GetPercentBSize(pStart, aFrame, isHorizontalAxis, pad))) {
+        sizeTakenByBoxSizing += pad;
+      }
+      if (GetDefiniteSize(pEnd, aFrame, aIsInlineAxis, aPercentageBasis, &pad) ||
+          (aPercentageBasis.isNothing() &&
+           GetPercentBSize(pEnd, aFrame, isHorizontalAxis, pad))) {
+        sizeTakenByBoxSizing += pad;
+      }
+    }
+  }
+  return sizeTakenByBoxSizing;
+}
+
 // Handles only -moz-max-content and -moz-min-content, and
 // -moz-fit-content for min-width and max-width, since the others
 // (-moz-fit-content for width, and -moz-available) have no effect on
@@ -4940,17 +5045,21 @@ AddStateBitToAncestors(nsIFrame* aFrame, nsFrameState aBit)
 }
 
 /* static */ nscoord
-nsLayoutUtils::IntrinsicForAxis(PhysicalAxis        aAxis,
-                                nsRenderingContext* aRenderingContext,
-                                nsIFrame*           aFrame,
-                                IntrinsicISizeType  aType,
-                                uint32_t            aFlags,
-                                nscoord             aMarginBoxMinSizeClamp)
+nsLayoutUtils::IntrinsicForAxis(PhysicalAxis              aAxis,
+                                nsRenderingContext*       aRenderingContext,
+                                nsIFrame*                 aFrame,
+                                IntrinsicISizeType        aType,
+                                const Maybe<LogicalSize>& aPercentageBasis,
+                                uint32_t                  aFlags,
+                                nscoord                   aMarginBoxMinSizeClamp)
 {
   NS_PRECONDITION(aFrame, "null frame");
   NS_PRECONDITION(aFrame->GetParent(),
                   "IntrinsicForAxis called on frame not in tree");
   NS_PRECONDITION(aType == MIN_ISIZE || aType == PREF_ISIZE, "bad type");
+  MOZ_ASSERT(aFrame->GetParent()->Type() != LayoutFrameType::GridContainer ||
+             aPercentageBasis.isSome(),
+             "grid layout should always pass a percentage basis");
 
   const bool horizontalAxis = MOZ_LIKELY(aAxis == eAxisHorizontal);
 #ifdef DEBUG_INTRINSIC_WIDTH
@@ -5014,6 +5123,7 @@ nsLayoutUtils::IntrinsicForAxis(PhysicalAxis        aAxis,
 
   PhysicalAxis ourInlineAxis =
     aFrame->GetWritingMode().PhysicalAxis(eLogicalAxisInline);
+  const bool isInlineAxis = aAxis == ourInlineAxis;
   // If we have a specified width (or a specified 'min-width' greater
   // than the specified 'max-width', which works out to the same thing),
   // don't even bother getting the frame's intrinsic width, because in
@@ -5043,7 +5153,7 @@ nsLayoutUtils::IntrinsicForAxis(PhysicalAxis        aAxis,
       // constraint is the max-content contribution which we shouldn't clamp.
       aMarginBoxMinSizeClamp = NS_MAXSIZE;
     }
-    if (MOZ_UNLIKELY(aAxis != ourInlineAxis)) {
+    if (MOZ_UNLIKELY(!isInlineAxis)) {
       IntrinsicSize intrinsicSize = aFrame->GetIntrinsicSize();
       const nsStyleCoord intrinsicBCoord =
         horizontalAxis ? intrinsicSize.width : intrinsicSize.height;
@@ -5105,21 +5215,23 @@ nsLayoutUtils::IntrinsicForAxis(PhysicalAxis        aAxis,
             NS_FRAME_DESCENDANT_INTRINSIC_ISIZE_DEPENDS_ON_BSIZE);
 
         nscoord bSizeTakenByBoxSizing =
-          GetBSizeTakenByBoxSizing(boxSizing, aFrame, horizontalAxis,
-                                   aFlags & IGNORE_PADDING);
-
+          GetDefiniteSizeTakenByBoxSizing(boxSizing, aFrame, !isInlineAxis,
+                                          aFlags & IGNORE_PADDING,
+                                          aPercentageBasis);
         // NOTE: This is only the minContentSize if we've been passed MIN_INTRINSIC_ISIZE
         // (which is fine, because this should only be used inside a check for that flag).
         nscoord minContentSize = result;
         nscoord h;
-        if (GetAbsoluteCoord(styleBSize, h) ||
-            GetPercentBSize(styleBSize, aFrame, horizontalAxis, h)) {
+        if (GetDefiniteSize(styleBSize, aFrame, !isInlineAxis, aPercentageBasis, &h) ||
+            (aPercentageBasis.isNothing() &&
+             GetPercentBSize(styleBSize, aFrame, horizontalAxis, h))) {
           h = std::max(0, h - bSizeTakenByBoxSizing);
           result = NSCoordMulDiv(h, ratioISize, ratioBSize);
         }
 
-        if (GetAbsoluteCoord(styleMaxBSize, h) ||
-            GetPercentBSize(styleMaxBSize, aFrame, horizontalAxis, h)) {
+        if (GetDefiniteSize(styleMaxBSize, aFrame, !isInlineAxis, aPercentageBasis, &h) ||
+            (aPercentageBasis.isNothing() &&
+             GetPercentBSize(styleMaxBSize, aFrame, horizontalAxis, h))) {
           h = std::max(0, h - bSizeTakenByBoxSizing);
           nscoord maxISize = NSCoordMulDiv(h, ratioISize, ratioBSize);
           if (maxISize < result) {
@@ -5130,8 +5242,9 @@ nsLayoutUtils::IntrinsicForAxis(PhysicalAxis        aAxis,
           }
         }
 
-        if (GetAbsoluteCoord(styleMinBSize, h) ||
-            GetPercentBSize(styleMinBSize, aFrame, horizontalAxis, h)) {
+        if (GetDefiniteSize(styleMinBSize, aFrame, !isInlineAxis, aPercentageBasis, &h) ||
+            (aPercentageBasis.isNothing() &&
+             GetPercentBSize(styleMinBSize, aFrame, horizontalAxis, h))) {
           h = std::max(0, h - bSizeTakenByBoxSizing);
           nscoord minISize = NSCoordMulDiv(h, ratioISize, ratioBSize);
           if (minISize > result) {
@@ -5158,8 +5271,8 @@ nsLayoutUtils::IntrinsicForAxis(PhysicalAxis        aAxis,
   }
 
   nsIFrame::IntrinsicISizeOffsetData offsets =
-    MOZ_LIKELY(aAxis == ourInlineAxis) ? aFrame->IntrinsicISizeOffsets()
-                                       : aFrame->IntrinsicBSizeOffsets();
+    MOZ_LIKELY(isInlineAxis) ? aFrame->IntrinsicISizeOffsets()
+                             : aFrame->IntrinsicBSizeOffsets();
   nscoord contentBoxSize = result;
   result = AddIntrinsicSizeOffset(aRenderingContext, aFrame, offsets, aType,
                                   boxSizing, result, min, styleISize,
@@ -5196,7 +5309,7 @@ nsLayoutUtils::IntrinsicForContainer(nsRenderingContext* aRenderingContext,
   // We want the size aFrame will contribute to its parent's inline-size.
   PhysicalAxis axis =
     aFrame->GetParent()->GetWritingMode().PhysicalAxis(eLogicalAxisInline);
-  return IntrinsicForAxis(axis, aRenderingContext, aFrame, aType, aFlags);
+  return IntrinsicForAxis(axis, aRenderingContext, aFrame, aType, Nothing(), aFlags);
 }
 
 /* static */ nscoord
diff --git a/layout/base/nsLayoutUtils.h b/layout/base/nsLayoutUtils.h
index d9580a3df..97fc410b0 100644
--- a/layout/base/nsLayoutUtils.h
+++ b/layout/base/nsLayoutUtils.h
@@ -1378,6 +1378,10 @@ public:
    * width, its 'width', 'min-width', and 'max-width' properties (or 'height'
    * variations if that's what matches aAxis) and its padding, border and margin
    * in the corresponding dimension.
+   * @param aPercentageBasis an optional percentage basis (in aFrame's WM).
+   *   Pass NS_UNCONSTRAINEDSIZE if the basis is indefinite in either/both axes.
+   *   If you pass Nothing() a percentage basis will be calculated from aFrame's
+   *   ancestors' computed size in the relevant axis, if needed.
    * @param aMarginBoxMinSizeClamp make the result fit within this margin-box
    * size by reducing the *content size* (flooring at zero).  This is used for:
    * https://drafts.csswg.org/css-grid/#min-size-auto
@@ -1396,6 +1400,7 @@ public:
                    nsRenderingContext*   aRenderingContext,
                    nsIFrame*             aFrame,
                    IntrinsicISizeType    aType,
+                   const mozilla::Maybe<mozilla::LogicalSize>& aPercentageBasis = mozilla::Nothing(),
                    uint32_t              aFlags = 0,
                    nscoord               aMarginBoxMinSizeClamp = NS_MAXSIZE);
   /**
diff --git a/layout/forms/nsFieldSetFrame.cpp b/layout/forms/nsFieldSetFrame.cpp
index befd41ee2..fc9f0571b 100644
--- a/layout/forms/nsFieldSetFrame.cpp
+++ b/layout/forms/nsFieldSetFrame.cpp
@@ -5,26 +5,22 @@
 
 #include "nsFieldSetFrame.h"
 
+#include <algorithm>
 #include "mozilla/gfx/2D.h"
+#include "mozilla/Likely.h"
+#include "mozilla/Maybe.h"
 #include "nsCSSAnonBoxes.h"
-#include "nsLayoutUtils.h"
-#include "nsLegendFrame.h"
 #include "nsCSSRendering.h"
-#include <algorithm>
-#include "nsIFrame.h"
-#include "nsPresContext.h"
-#include "mozilla/RestyleManager.h"
-#include "nsGkAtoms.h"
-#include "nsStyleConsts.h"
 #include "nsDisplayList.h"
+#include "nsGkAtoms.h"
+#include "nsIFrameInlines.h"
+#include "nsLayoutUtils.h"
+#include "nsLegendFrame.h"
 #include "nsRenderingContext.h"
-#include "nsIScrollableFrame.h"
-#include "mozilla/Likely.h"
-#include "mozilla/Maybe.h"
+#include "nsStyleConsts.h"
 
 using namespace mozilla;
 using namespace mozilla::gfx;
-using namespace mozilla::image;
 using namespace mozilla::layout;
 
 nsContainerFrame*
@@ -126,7 +122,7 @@ void
 nsDisplayFieldSetBorderBackground::Paint(nsDisplayListBuilder* aBuilder,
                                          nsRenderingContext* aCtx)
 {
-  DrawResult result = static_cast<nsFieldSetFrame*>(mFrame)->
+  image::DrawResult result = static_cast<nsFieldSetFrame*>(mFrame)->
     PaintBorder(aBuilder, *aCtx, ToReferenceFrame(), mVisibleRect);
 
   nsDisplayItemGenericImageGeometry::UpdateDrawResult(this, result);
@@ -210,7 +206,7 @@ nsFieldSetFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
   contentDisplayItems.MoveTo(aLists);
 }
 
-DrawResult
+image::DrawResult
 nsFieldSetFrame::PaintBorder(
   nsDisplayListBuilder* aBuilder,
   nsRenderingContext& aRenderingContext,
@@ -695,9 +691,50 @@ nsFieldSetFrame::AccessibleType()
 #endif
 
 nscoord
-nsFieldSetFrame::GetLogicalBaseline(WritingMode aWritingMode) const
+nsFieldSetFrame::GetLogicalBaseline(WritingMode aWM) const
+{
+  switch (StyleDisplay()->mDisplay) {
+    case mozilla::StyleDisplay::Grid:
+    case mozilla::StyleDisplay::InlineGrid:
+    case mozilla::StyleDisplay::Flex:
+    case mozilla::StyleDisplay::InlineFlex:
+      return BaselineBOffset(aWM, BaselineSharingGroup::eFirst,
+                             AlignmentContext::eInline);
+    default:
+      return BSize(aWM) - BaselineBOffset(aWM, BaselineSharingGroup::eLast,
+                                          AlignmentContext::eInline);
+  }
+}
+
+bool
+nsFieldSetFrame::GetVerticalAlignBaseline(WritingMode aWM,
+                                          nscoord* aBaseline) const
 {
   nsIFrame* inner = GetInner();
-  return inner->BStart(aWritingMode, GetParent()->GetSize()) +
-    inner->GetLogicalBaseline(aWritingMode);
+  MOZ_ASSERT(!inner->GetWritingMode().IsOrthogonalTo(aWM));
+  if (!inner->GetVerticalAlignBaseline(aWM, aBaseline)) {
+    return false;
+  }
+  nscoord innerBStart = inner->BStart(aWM, GetSize());
+  *aBaseline += innerBStart;
+  return true;
+}
+
+bool
+nsFieldSetFrame::GetNaturalBaselineBOffset(WritingMode          aWM,
+                                           BaselineSharingGroup aBaselineGroup,
+                                           nscoord*             aBaseline) const
+{
+  nsIFrame* inner = GetInner();
+  MOZ_ASSERT(!inner->GetWritingMode().IsOrthogonalTo(aWM));
+  if (!inner->GetNaturalBaselineBOffset(aWM, aBaselineGroup, aBaseline)) {
+    return false;
+  }
+  nscoord innerBStart = inner->BStart(aWM, GetSize());
+  if (aBaselineGroup == BaselineSharingGroup::eFirst) {
+    *aBaseline += innerBStart;
+  } else {
+    *aBaseline += BSize(aWM) - (innerBStart + inner->BSize(aWM));
+  }
+  return true;
 }
diff --git a/layout/forms/nsFieldSetFrame.h b/layout/forms/nsFieldSetFrame.h
index 54eaf678f..5eb67c320 100644
--- a/layout/forms/nsFieldSetFrame.h
+++ b/layout/forms/nsFieldSetFrame.h
@@ -7,7 +7,7 @@
 #define nsFieldSetFrame_h___
 
 #include "mozilla/Attributes.h"
-#include "imgIContainer.h"
+#include "DrawResult.h"
 #include "nsContainerFrame.h"
 
 class nsFieldSetFrame final : public nsContainerFrame
@@ -33,7 +33,6 @@ public:
               const mozilla::LogicalSize& aBorder,
               const mozilla::LogicalSize& aPadding,
               ComputeSizeFlags aFlags) override;
-  virtual nscoord GetLogicalBaseline(mozilla::WritingMode aWritingMode) const override;
 
   /**
    * The area to paint box-shadows around.  It's the border rect except
@@ -46,6 +45,13 @@ public:
                       const ReflowInput& aReflowInput,
                       nsReflowStatus&          aStatus) override;
                                
+  nscoord GetLogicalBaseline(mozilla::WritingMode aWM) const override;
+  bool GetVerticalAlignBaseline(mozilla::WritingMode aWM,
+                                nscoord* aBaseline) const override;
+  bool GetNaturalBaselineBOffset(mozilla::WritingMode aWM,
+                                 BaselineSharingGroup aBaselineGroup,
+                                 nscoord* aBaseline) const override;
+
   virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,
                                 const nsRect&           aDirtyRect,
                                 const nsDisplayListSet& aLists) override;
diff --git a/layout/forms/nsHTMLButtonControlFrame.cpp b/layout/forms/nsHTMLButtonControlFrame.cpp
index ef9459ef2..2e4fa9f67 100644
--- a/layout/forms/nsHTMLButtonControlFrame.cpp
+++ b/layout/forms/nsHTMLButtonControlFrame.cpp
@@ -418,6 +418,47 @@ nsHTMLButtonControlFrame::ReflowButtonContents(nsPresContext* aPresContext,
   aButtonDesiredSize.SetOverflowAreasToDesiredBounds();
 }
 
+bool
+nsHTMLButtonControlFrame::GetVerticalAlignBaseline(mozilla::WritingMode aWM,
+                                                   nscoord* aBaseline) const
+{
+  nsIFrame* inner = mFrames.FirstChild();
+  if (MOZ_UNLIKELY(inner->GetWritingMode().IsOrthogonalTo(aWM))) {
+    return false;
+  }
+  if (!inner->GetVerticalAlignBaseline(aWM, aBaseline)) {
+    // <input type=color> has an empty block frame as inner frame
+    *aBaseline = inner->
+      SynthesizeBaselineBOffsetFromBorderBox(aWM, BaselineSharingGroup::eFirst);
+  }
+  nscoord innerBStart = inner->BStart(aWM, GetSize());
+  *aBaseline += innerBStart;
+  return true;
+}
+
+bool
+nsHTMLButtonControlFrame::GetNaturalBaselineBOffset(mozilla::WritingMode aWM,
+                                         BaselineSharingGroup aBaselineGroup,
+                                         nscoord* aBaseline) const
+{
+  nsIFrame* inner = mFrames.FirstChild();
+  if (MOZ_UNLIKELY(inner->GetWritingMode().IsOrthogonalTo(aWM))) {
+    return false;
+  }
+  if (!inner->GetNaturalBaselineBOffset(aWM, aBaselineGroup, aBaseline)) {
+    // <input type=color> has an empty block frame as inner frame
+    *aBaseline = inner->
+      SynthesizeBaselineBOffsetFromBorderBox(aWM, aBaselineGroup);
+  }
+  nscoord innerBStart = inner->BStart(aWM, GetSize());
+  if (aBaselineGroup == BaselineSharingGroup::eFirst) {
+    *aBaseline += innerBStart;
+  } else {
+    *aBaseline += BSize(aWM) - (innerBStart + inner->BSize(aWM));
+  }
+  return true;
+}
+
 nsresult nsHTMLButtonControlFrame::SetFormProperty(nsIAtom* aName, const nsAString& aValue)
 {
   if (nsGkAtoms::value == aName) {
diff --git a/layout/forms/nsHTMLButtonControlFrame.h b/layout/forms/nsHTMLButtonControlFrame.h
index 96ad0f366..432afa12c 100644
--- a/layout/forms/nsHTMLButtonControlFrame.h
+++ b/layout/forms/nsHTMLButtonControlFrame.h
@@ -39,6 +39,13 @@ public:
                       const ReflowInput& aReflowInput,
                       nsReflowStatus&          aStatus) override;
 
+  bool GetVerticalAlignBaseline(mozilla::WritingMode aWM,
+                                nscoord* aBaseline) const override;
+
+  bool GetNaturalBaselineBOffset(mozilla::WritingMode aWM,
+                                 BaselineSharingGroup aBaselineGroup,
+                                 nscoord* aBaseline) const override;
+
   virtual nsresult HandleEvent(nsPresContext* aPresContext, 
                                mozilla::WidgetGUIEvent* aEvent,
                                nsEventStatus* aEventStatus) override;
diff --git a/layout/forms/nsLegendFrame.h b/layout/forms/nsLegendFrame.h
index 5f5e1e03e..a9e11cbbe 100644
--- a/layout/forms/nsLegendFrame.h
+++ b/layout/forms/nsLegendFrame.h
@@ -9,7 +9,8 @@
 #include "mozilla/Attributes.h"
 #include "nsBlockFrame.h"
 
-class nsLegendFrame : public nsBlockFrame {
+class nsLegendFrame final : public nsBlockFrame
+{
 public:
   NS_DECL_QUERYFRAME_TARGET(nsLegendFrame)
   NS_DECL_QUERYFRAME
@@ -30,7 +31,7 @@ public:
   virtual nsresult GetFrameName(nsAString& aResult) const override;
 #endif
 
-  int32_t GetLogicalAlign(WritingMode aCBWM);
+  int32_t GetLogicalAlign(mozilla::WritingMode aCBWM);
 };
 
 
diff --git a/layout/forms/nsTextControlFrame.cpp b/layout/forms/nsTextControlFrame.cpp
index f85bc2a80..a7f7d40a8 100644
--- a/layout/forms/nsTextControlFrame.cpp
+++ b/layout/forms/nsTextControlFrame.cpp
@@ -106,6 +106,7 @@ private:
 
 nsTextControlFrame::nsTextControlFrame(nsStyleContext* aContext)
   : nsContainerFrame(aContext)
+  , mFirstBaseline(NS_INTRINSIC_WIDTH_UNKNOWN)
   , mEditorHasBeenInitialized(false)
   , mIsProcessing(false)
 #ifdef DEBUG
@@ -538,20 +539,20 @@ nsTextControlFrame::Reflow(nsPresContext*   aPresContext,
               aReflowInput.ComputedLogicalBorderPadding().BStartEnd(wm));
   aDesiredSize.SetSize(wm, finalSize);
 
-  // computation of the ascent wrt the input height
+  // Calculate the baseline and store it in mFirstBaseline.
   nscoord lineHeight = aReflowInput.ComputedBSize();
   float inflation = nsLayoutUtils::FontSizeInflationFor(this);
   if (!IsSingleLineTextControl()) {
     lineHeight = ReflowInput::CalcLineHeight(GetContent(), StyleContext(),
-                                                   NS_AUTOHEIGHT, inflation);
+                                             NS_AUTOHEIGHT, inflation);
   }
   RefPtr<nsFontMetrics> fontMet =
     nsLayoutUtils::GetFontMetricsForFrame(this, inflation);
-  // now adjust for our borders and padding
-  aDesiredSize.SetBlockStartAscent(
+  mFirstBaseline =
     nsLayoutUtils::GetCenteredFontBaseline(fontMet, lineHeight,
                                            wm.IsLineInverted()) +
-    aReflowInput.ComputedLogicalBorderPadding().BStart(wm));
+    aReflowInput.ComputedLogicalBorderPadding().BStart(wm);
+  aDesiredSize.SetBlockStartAscent(mFirstBaseline);
 
   // overflow handling
   aDesiredSize.SetOverflowAreasToDesiredBounds();
diff --git a/layout/forms/nsTextControlFrame.h b/layout/forms/nsTextControlFrame.h
index a76cba514..9d4d0b77c 100644
--- a/layout/forms/nsTextControlFrame.h
+++ b/layout/forms/nsTextControlFrame.h
@@ -62,6 +62,29 @@ public:
                       const ReflowInput& aReflowInput,
                       nsReflowStatus&          aStatus) override;
 
+  bool GetVerticalAlignBaseline(mozilla::WritingMode aWM,
+                                nscoord* aBaseline) const override
+  {
+    return GetNaturalBaselineBOffset(aWM, BaselineSharingGroup::eFirst, aBaseline);
+  }
+
+  bool GetNaturalBaselineBOffset(mozilla::WritingMode aWM,
+                                 BaselineSharingGroup aBaselineGroup,
+                                 nscoord* aBaseline) const override
+  {
+    if (!IsSingleLineTextControl()) {
+      return false;
+    }
+    NS_ASSERTION(mFirstBaseline != NS_INTRINSIC_WIDTH_UNKNOWN,
+                 "please call Reflow before asking for the baseline");
+    if (aBaselineGroup == BaselineSharingGroup::eFirst) {
+      *aBaseline = mFirstBaseline;
+    } else {
+      *aBaseline = BSize(aWM) - mFirstBaseline;
+    }
+    return true;
+  }
+
   virtual nsSize GetXULMinSize(nsBoxLayoutState& aBoxLayoutState) override;
   virtual bool IsXULCollapsed() override;
 
@@ -87,6 +110,14 @@ public:
       ~(nsIFrame::eReplaced | nsIFrame::eReplacedContainsBlock));
   }
 
+#ifdef DEBUG
+  void MarkIntrinsicISizesDirty() override
+  {
+    // Need another Reflow to have a correct baseline value again.
+    mFirstBaseline = NS_INTRINSIC_WIDTH_UNKNOWN;
+  }
+#endif
+
   // nsIAnonymousContentCreator
   virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) override;
   virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
@@ -300,6 +331,10 @@ private:
   }
 
 private:
+  // Our first baseline, or NS_INTRINSIC_WIDTH_UNKNOWN if we have a pending
+  // Reflow.
+  nscoord mFirstBaseline;
+
   // these packed bools could instead use the high order bits on mState, saving 4 bytes 
   bool mEditorHasBeenInitialized;
   bool mIsProcessing;
diff --git a/layout/generic/ReflowInput.cpp b/layout/generic/ReflowInput.cpp
index 42f4a24b5..a8756cea2 100644
--- a/layout/generic/ReflowInput.cpp
+++ b/layout/generic/ReflowInput.cpp
@@ -93,6 +93,9 @@ ReflowInput::ReflowInput(nsPresContext*       aPresContext,
   if (aFlags & B_CLAMP_MARGIN_BOX_MIN_SIZE) {
     mFlags.mBClampMarginBoxMinSize = true;
   }
+  if (aFlags & I_APPLY_AUTO_MIN_SIZE) {
+    mFlags.mApplyAutoMinSize = true;
+  }
 
   if (!(aFlags & CALLER_WILL_INIT)) {
     Init(aPresContext);
@@ -242,6 +245,7 @@ ReflowInput::ReflowInput(
   mFlags.mIOffsetsNeedCSSAlign = mFlags.mBOffsetsNeedCSSAlign = false;
   mFlags.mIClampMarginBoxMinSize = !!(aFlags & I_CLAMP_MARGIN_BOX_MIN_SIZE);
   mFlags.mBClampMarginBoxMinSize = !!(aFlags & B_CLAMP_MARGIN_BOX_MIN_SIZE);
+  mFlags.mApplyAutoMinSize = !!(aFlags & I_APPLY_AUTO_MIN_SIZE);
 
   mDiscoveredClearance = nullptr;
   mPercentBSizeObserver = (aParentReflowInput.mPercentBSizeObserver &&
@@ -1662,6 +1666,10 @@ ReflowInput::InitAbsoluteConstraints(nsPresContext* aPresContext,
     computeSizeFlags = ComputeSizeFlags(computeSizeFlags |
                          ComputeSizeFlags::eBClampMarginBoxMinSize);
   }
+  if (mFlags.mApplyAutoMinSize) {
+    computeSizeFlags = ComputeSizeFlags(computeSizeFlags |
+                         ComputeSizeFlags::eIApplyAutoMinSize);
+  }
   if (mFlags.mShrinkWrap) {
     computeSizeFlags =
       ComputeSizeFlags(computeSizeFlags | ComputeSizeFlags::eShrinkWrap);
@@ -2375,6 +2383,10 @@ ReflowInput::InitConstraints(nsPresContext*     aPresContext,
         computeSizeFlags = ComputeSizeFlags(computeSizeFlags |
                              ComputeSizeFlags::eBClampMarginBoxMinSize);
       }
+      if (mFlags.mApplyAutoMinSize) {
+        computeSizeFlags = ComputeSizeFlags(computeSizeFlags |
+                             ComputeSizeFlags::eIApplyAutoMinSize);
+      }
       if (mFlags.mShrinkWrap) {
         computeSizeFlags =
           ComputeSizeFlags(computeSizeFlags | ComputeSizeFlags::eShrinkWrap);
diff --git a/layout/generic/ReflowInput.h b/layout/generic/ReflowInput.h
index e42508646..09c980b72 100644
--- a/layout/generic/ReflowInput.h
+++ b/layout/generic/ReflowInput.h
@@ -220,6 +220,7 @@ public:
     uint32_t mStaticPosIsCBOrigin:1; // the STATIC_POS_IS_CB_ORIGIN ctor flag
     uint32_t mIClampMarginBoxMinSize:1; // the I_CLAMP_MARGIN_BOX_MIN_SIZE ctor flag
     uint32_t mBClampMarginBoxMinSize:1; // the B_CLAMP_MARGIN_BOX_MIN_SIZE ctor flag
+    uint32_t mApplyAutoMinSize : 1;       // the I_APPLY_AUTO_MIN_SIZE ctor flag
 
     // If set, the following two flags indicate that:
     // (1) this frame is absolutely-positioned (or fixed-positioned).
@@ -738,6 +739,9 @@ public:
 
     // Pass ComputeSizeFlags::eBClampMarginBoxMinSize to ComputeSize().
     B_CLAMP_MARGIN_BOX_MIN_SIZE = (1<<6),
+
+    // Pass ComputeSizeFlags::eIApplyAutoMinSize to ComputeSize().
+    I_APPLY_AUTO_MIN_SIZE = (1<<7),
   };
 
   // This method initializes various data members. It is automatically
diff --git a/layout/generic/nsFrame.cpp b/layout/generic/nsFrame.cpp
index 69791d5c5..418fa16b7 100644
--- a/layout/generic/nsFrame.cpp
+++ b/layout/generic/nsFrame.cpp
@@ -4781,7 +4781,7 @@ nsFrame::ComputeSize(nsRenderingContext* aRenderingContext,
       ComputeISizeValue(aRenderingContext, aCBSize.ISize(aWM),
                         boxSizingAdjust.ISize(aWM), boxSizingToMarginEdgeISize,
                         minISizeCoord, aFlags);
-  } else if (MOZ_UNLIKELY(isGridItem)) {
+  } else if (MOZ_UNLIKELY(aFlags & eIApplyAutoMinSize)) {
     // This implements "Implied Minimum Size of Grid Items".
     // https://drafts.csswg.org/css-grid/#min-size-auto
     minISize = std::min(maxISize, GetMinISize(aRenderingContext));
diff --git a/layout/generic/nsGridContainerFrame.cpp b/layout/generic/nsGridContainerFrame.cpp
index 71d5bba21..8f117b5ab 100644
--- a/layout/generic/nsGridContainerFrame.cpp
+++ b/layout/generic/nsGridContainerFrame.cpp
@@ -818,8 +818,11 @@ struct nsGridContainerFrame::GridItemInfo
     // Ditto *-content:[last ]baseline. Mutually exclusive w. eSelfBaseline.
     eContentBaseline =       0x10,
     eAllBaselineBits = eIsBaselineAligned | eSelfBaseline | eContentBaseline,
+    // Should apply Automatic Minimum Size per:
+    // https://drafts.csswg.org/css-grid/#min-size-auto
+    eApplyAutoMinSize =      0x20,
     // Clamp per https://drafts.csswg.org/css-grid/#min-size-auto
-    eClampMarginBoxMinSize = 0x20,
+    eClampMarginBoxMinSize = 0x40,
   };
 
   explicit GridItemInfo(nsIFrame* aFrame,
@@ -851,11 +854,11 @@ struct nsGridContainerFrame::GridItemInfo
     return aAlign;
   }
 
-  // Return true if we should we clamp this item's Automatic Minimum Size.
+  // Return true if we should apply Automatic Minimum Size to this item.
   // https://drafts.csswg.org/css-grid/#min-size-auto
-  bool ShouldClampMinSize(WritingMode aContainerWM,
-                          LogicalAxis aContainerAxis,
-                          nscoord aPercentageBasis) const
+  bool ShouldApplyAutoMinSize(WritingMode aContainerWM,
+                              LogicalAxis aContainerAxis,
+                              nscoord aPercentageBasis) const
   {
     const auto pos = mFrame->StylePosition();
     const auto& size = aContainerAxis == eLogicalAxisInline ?
@@ -2090,6 +2093,18 @@ struct MOZ_STACK_CLASS nsGridContainerFrame::GridReflowInput
                            SizingConstraint   aConstraint);
 
   /**
+   * Return the percentage basis for a grid item in its writing-mode.
+   * If aAxis is eLogicalAxisInline then we return NS_UNCONSTRAINEDSIZE in
+   * both axes since we know all track sizes are indefinite at this point
+   * (we calculate column sizes before row sizes).  Otherwise, assert that
+   * column sizes are known and calculate the size for aGridItem.mArea.mCols
+   * and use NS_UNCONSTRAINEDSIZE in the other axis.
+   * @param aAxis the axis we're currently calculating track sizes for
+   */
+  LogicalSize PercentageBasisFor(LogicalAxis aAxis,
+                                 const GridItemInfo& aGridItem) const;
+
+  /**
    * Return the containing block for a grid item occupying aArea.
    */
   LogicalRect ContainingBlockFor(const GridArea& aArea) const;
@@ -3731,18 +3746,20 @@ MeasuringReflow(nsIFrame*           aChild,
  * the child's margin-box) in aAxis.
  */
 static nscoord
-ContentContribution(const GridItemInfo&    aGridItem,
-                    const GridReflowInput& aState,
-                    nsRenderingContext*    aRC,
-                    WritingMode            aCBWM,
-                    LogicalAxis            aAxis,
-                    IntrinsicISizeType     aConstraint,
-                    nscoord                aMinSizeClamp = NS_MAXSIZE,
-                    uint32_t               aFlags = 0)
+ContentContribution(const GridItemInfo&       aGridItem,
+                    const GridReflowInput&    aState,
+                    nsRenderingContext*       aRC,
+                    WritingMode               aCBWM,
+                    LogicalAxis               aAxis,
+                    const Maybe<LogicalSize>& aPercentageBasis,
+                    IntrinsicISizeType        aConstraint,
+                    nscoord                   aMinSizeClamp = NS_MAXSIZE,
+                    uint32_t                  aFlags = 0)
 {
   nsIFrame* child = aGridItem.mFrame;
   PhysicalAxis axis(aCBWM.PhysicalAxis(aAxis));
   nscoord size = nsLayoutUtils::IntrinsicForAxis(axis, aRC, child, aConstraint,
+                   aPercentageBasis,
                    aFlags | nsLayoutUtils::BAIL_IF_REFLOW_NEEDED |
                             nsLayoutUtils::ADD_PERCENTS,
                    aMinSizeClamp);
@@ -3812,6 +3829,10 @@ struct CachedIntrinsicSizes
   Maybe<nscoord> mMinSize;
   Maybe<nscoord> mMinContentContribution;
   Maybe<nscoord> mMaxContentContribution;
+
+  // The item's percentage basis for intrinsic sizing purposes.
+  Maybe<LogicalSize> mPercentageBasis;
+
   // "if the grid item spans only grid tracks that have a fixed max track
   // sizing function, its automatic minimum size in that dimension is
   // further clamped to less than or equal to the size necessary to fit its
@@ -3832,7 +3853,11 @@ MinContentContribution(const GridItemInfo&    aGridItem,
   if (aCache->mMinContentContribution.isSome()) {
     return aCache->mMinContentContribution.value();
   }
+  if (aCache->mPercentageBasis.isNothing()) {
+    aCache->mPercentageBasis.emplace(aState.PercentageBasisFor(aAxis, aGridItem));
+  }
   nscoord s = ContentContribution(aGridItem, aState, aRC, aCBWM, aAxis,
+                                  aCache->mPercentageBasis,
                                   nsLayoutUtils::MIN_ISIZE,
                                   aCache->mMinSizeClamp);
   aCache->mMinContentContribution.emplace(s);
@@ -3850,7 +3875,11 @@ MaxContentContribution(const GridItemInfo&    aGridItem,
   if (aCache->mMaxContentContribution.isSome()) {
     return aCache->mMaxContentContribution.value();
   }
+  if (aCache->mPercentageBasis.isNothing()) {
+    aCache->mPercentageBasis.emplace(aState.PercentageBasisFor(aAxis, aGridItem));
+  }
   nscoord s = ContentContribution(aGridItem, aState, aRC, aCBWM, aAxis,
+                                  aCache->mPercentageBasis,
                                   nsLayoutUtils::PREF_ISIZE,
                                   aCache->mMinSizeClamp);
   aCache->mMaxContentContribution.emplace(s);
@@ -3904,7 +3933,11 @@ MinSize(const GridItemInfo&    aGridItem,
        child->StyleDisplay()->mOverflowX == NS_STYLE_OVERFLOW_VISIBLE)) {
     // Now calculate the "content size" part and return whichever is smaller.
     MOZ_ASSERT(unit != eStyleUnit_Enumerated || sz == NS_UNCONSTRAINEDSIZE);
+    if (aCache->mPercentageBasis.isNothing()) {
+      aCache->mPercentageBasis.emplace(aState.PercentageBasisFor(aAxis, aGridItem));
+    }
     sz = std::min(sz, ContentContribution(aGridItem, aState, aRC, aCBWM, aAxis,
+                                          aCache->mPercentageBasis,
                                           nsLayoutUtils::MIN_ISIZE,
                                           aCache->mMinSizeClamp,
                                           nsLayoutUtils::MIN_INTRINSIC_ISIZE));
@@ -3977,9 +4010,9 @@ nsGridContainerFrame::Tracks::ResolveIntrinsicSizeStep1(
   WritingMode wm = aState.mWM;
   // Calculate data for "Automatic Minimum Size" clamping, if needed.
   bool needed = ((sz.mState & TrackSize::eIntrinsicMinSizing) ||
-                 aConstraint == SizingConstraint::eNoConstraint);
-  if (needed && TrackSize::IsDefiniteMaxSizing(sz.mState) &&
-      aGridItem.ShouldClampMinSize(wm, mAxis, aPercentageBasis)) {
+                 aConstraint == SizingConstraint::eNoConstraint) &&
+                (aGridItem.mState[mAxis] & ItemState::eApplyAutoMinSize);
+  if (needed && TrackSize::IsDefiniteMaxSizing(sz.mState)) {
     if (sz.mState & TrackSize::eIntrinsicMinSizing) {
       auto maxCoord = aFunctions.MaxSizingFor(aRange.mStart);
       cache.mMinSizeClamp =
@@ -4382,6 +4415,14 @@ nsGridContainerFrame::Tracks::ResolveIntrinsicSize(
   iter.Reset();
   for (; !iter.AtEnd(); iter.Next()) {
     auto& gridItem = aGridItems[iter.GridItemIndex()];
+
+    // Check if we need to apply "Automatic Minimum Size" and cache it.
+    MOZ_ASSERT(!(gridItem.mState[mAxis] & ItemState::eApplyAutoMinSize),
+               "Why is eApplyAutoMinSize set already?");
+    if (gridItem.ShouldApplyAutoMinSize(wm, mAxis, aPercentageBasis)) {
+      gridItem.mState[mAxis] |= ItemState::eApplyAutoMinSize;
+    }
+
     const GridArea& area = gridItem.mArea;
     const LineRange& lineRange = area.*aRange;
     uint32_t span = lineRange.Extent();
@@ -4407,9 +4448,9 @@ nsGridContainerFrame::Tracks::ResolveIntrinsicSize(
         CachedIntrinsicSizes cache;
         // Calculate data for "Automatic Minimum Size" clamping, if needed.
         bool needed = ((state & TrackSize::eIntrinsicMinSizing) ||
-                       aConstraint == SizingConstraint::eNoConstraint);
-        if (needed && TrackSize::IsDefiniteMaxSizing(state) &&
-            gridItem.ShouldClampMinSize(wm, mAxis, aPercentageBasis)) {
+                       aConstraint == SizingConstraint::eNoConstraint) &&
+                      (gridItem.mState[mAxis] & ItemState::eApplyAutoMinSize);
+        if (needed && TrackSize::IsDefiniteMaxSizing(state)) {
           nscoord minSizeClamp = 0;
           for (auto i = lineRange.mStart, end = lineRange.mEnd; i < end; ++i) {
             auto maxCoord = aFunctions.MaxSizingFor(i);
@@ -4445,11 +4486,14 @@ nsGridContainerFrame::Tracks::ResolveIntrinsicSize(
           gridItem.mState[mAxis] |= ItemState::eIsFlexing;
         } else if (aConstraint == SizingConstraint::eNoConstraint &&
                    TrackSize::IsDefiniteMaxSizing(state) &&
-                   gridItem.ShouldClampMinSize(wm, mAxis, aPercentageBasis)) {
+                   (gridItem.mState[mAxis] & ItemState::eApplyAutoMinSize)) {
           gridItem.mState[mAxis] |= ItemState::eClampMarginBoxMinSize;
         }
       }
     }
+    MOZ_ASSERT(!(gridItem.mState[mAxis] & ItemState::eClampMarginBoxMinSize) ||
+               (gridItem.mState[mAxis] & ItemState::eApplyAutoMinSize),
+               "clamping only applies to Automatic Minimum Size");
   }
 
   // Step 2.
@@ -4707,7 +4751,8 @@ nsGridContainerFrame::Tracks::FindUsedFlexFraction(
     const GridItemInfo& item = aGridItems[iter.GridItemIndex()];
     if (item.mState[mAxis] & ItemState::eIsFlexing) {
       // XXX optimize: bug 1194446
-      nscoord spaceToFill = ContentContribution(item, aState, rc, wm, mAxis,
+      auto pb = Some(aState.PercentageBasisFor(mAxis, item));
+      nscoord spaceToFill = ContentContribution(item, aState, rc, wm, mAxis, pb,
                                                 nsLayoutUtils::PREF_ISIZE);
       if (spaceToFill <= 0) {
         continue;
@@ -5038,6 +5083,25 @@ nsGridContainerFrame::LineRange::ToPositionAndLengthForAbsPos(
   }
 }
 
+LogicalSize
+nsGridContainerFrame::GridReflowInput::PercentageBasisFor(
+  LogicalAxis aAxis,
+  const GridItemInfo& aGridItem) const
+{
+  auto wm = aGridItem.mFrame->GetWritingMode();
+  if (aAxis == eLogicalAxisInline) {
+    return LogicalSize(wm, NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
+  }
+  // Note: for now, we only resolve transferred percentages to row sizing.
+  // We may need to adjust these assertions once we implement bug 1300366.
+  MOZ_ASSERT(mCols.mCanResolveLineRangeSize);
+  MOZ_ASSERT(!mRows.mCanResolveLineRangeSize);
+  nscoord colSize = aGridItem.mArea.mCols.ToLength(mCols.mSizes);
+  nscoord rowSize = NS_UNCONSTRAINEDSIZE;
+  return !wm.IsOrthogonalTo(mWM) ?
+    LogicalSize(wm, colSize, rowSize) : LogicalSize(wm, rowSize, colSize);
+}
+
 LogicalRect
 nsGridContainerFrame::GridReflowInput::ContainingBlockFor(const GridArea& aArea) const
 {
@@ -5231,6 +5295,9 @@ nsGridContainerFrame::ReflowInFlowChild(nsIFrame*              aChild,
     } else {
       aChild->Properties().Delete(BClampMarginBoxMinSizeProperty());
     }
+    if ((aGridItemInfo->mState[childIAxis] & ItemState::eApplyAutoMinSize)) {
+      flags |= ReflowInput::I_APPLY_AUTO_MIN_SIZE;
+    }
   }
 
   if (!isConstrainedBSize) {
diff --git a/layout/generic/nsIFrame.h b/layout/generic/nsIFrame.h
index 50eb958e0..2acafa882 100644
--- a/layout/generic/nsIFrame.h
+++ b/layout/generic/nsIFrame.h
@@ -2105,6 +2105,14 @@ public:
      */
     eIClampMarginBoxMinSize = 1 << 2, // clamp in our inline axis
     eBClampMarginBoxMinSize = 1 << 3, // clamp in our block axis
+    /**
+     * The frame is stretching (per CSS Box Alignment) and doesn't have an
+     * Automatic Minimum Size in the indicated axis.
+     * (may be used for both flex/grid items, but currently only used for Grid)
+     * https://drafts.csswg.org/css-grid/#min-size-auto
+     * https://drafts.csswg.org/css-align-3/#valdef-justify-self-stretch
+     */
+    eIApplyAutoMinSize = 1 << 4, // only has an effect when eShrinkWrap is false
   };
 
   /**
diff --git a/layout/reftests/bugs/315920-17.html b/layout/reftests/bugs/315920-17.html
index 1681754a5..6d9180144 100644
--- a/layout/reftests/bugs/315920-17.html
+++ b/layout/reftests/bugs/315920-17.html
@@ -1,5 +1,5 @@
 <!DOCTYPE html>
-<html>
+<html class="reftest-wait">
   <head>
     <style>
       input ~ label {color: red}
@@ -8,9 +8,7 @@
       input:checked:default + label {color: green}
     </style>
   </head>
-  <body onload='document.getElementById("two").setAttribute("checked", "true");
-                document.getElementById("one").setAttribute("checked", "checked");
-                document.getElementById("two").removeAttribute("checked");'>
+  <body>
     <form>
       <input type="checkbox" name="group1" id="one" value="1"/>
       <label for="one">Should be no red</label><br>
@@ -19,5 +17,14 @@
       <input type="checkbox" name="group1" id="three" value="3"/>
       <label for="three">Should be no red</label>
     </form>
+<script>
+function doTest() {
+  document.getElementById("two").setAttribute("checked", "true");
+  document.getElementById("one").setAttribute("checked", "checked");
+  document.getElementById("two").removeAttribute("checked");
+  setTimeout(function () { document.documentElement.removeAttribute("class"); }, 0);
+}
+window.addEventListener("MozReftestInvalidate", doTest);
+</script>
   </body>
 </html>
diff --git a/layout/reftests/css-grid/grid-auto-min-sizing-min-content-min-size-004-ref.html b/layout/reftests/css-grid/grid-auto-min-sizing-min-content-min-size-004-ref.html
index fc74cd214..caef8b031 100644
--- a/layout/reftests/css-grid/grid-auto-min-sizing-min-content-min-size-004-ref.html
+++ b/layout/reftests/css-grid/grid-auto-min-sizing-min-content-min-size-004-ref.html
@@ -36,7 +36,7 @@ var rowtest = [
 "min-width:80%; max-height:20px", "min-width:50%", "margin-left: 50px; width:50%"
 ];
 var results = [
-"0/2px", "0/2px", "0/4px", "0/2px", "0/2px", "0/2px", "24px/2px", "20px/2px", "20px/2px", "24px/2px", "24px/52px"
+"0/2px", "0/2px", "0/4px", "0/2px", "0/2px", "0/2px", "12px/2px", "20px/2px", "20px/2px", "24px/2px", "24px/52px"
 ];
 var item_height = [
 "0", "0", "0", "0", "0", "0", "12px", "20px", "20px", "24px", "312px"
diff --git a/layout/reftests/css-grid/grid-auto-min-sizing-transferred-size-004-ref.html b/layout/reftests/css-grid/grid-auto-min-sizing-transferred-size-004-ref.html
index c5d8a68ff..36a2d4920 100644
--- a/layout/reftests/css-grid/grid-auto-min-sizing-transferred-size-004-ref.html
+++ b/layout/reftests/css-grid/grid-auto-min-sizing-transferred-size-004-ref.html
@@ -36,7 +36,7 @@ var rowtest = [
 "min-width:80%; max-height:20px", "min-width:50%", "margin-left: 50px; width:50%"
 ];
 var results = [
-"0/2px", "0/2px", "0/4px", "0/2px", "0/2px", "0/2px", "24px/2px", "20px/2px", "20px/2px", "24px/2px", "24px/52px"
+"0/2px", "0/2px", "0/4px", "0/2px", "0/2px", "0/2px", "12px/2px", "20px/2px", "20px/2px", "24px/2px", "24px/52px"
 ];
 var item_height = [
 "0", "0", "0", "0", "0", "0", "12px", "20px", "20px", "24px", "312px"
diff --git a/layout/reftests/css-grid/grid-item-overflow-stretch-001-ref.html b/layout/reftests/css-grid/grid-item-overflow-stretch-001-ref.html
new file mode 100644
index 000000000..463bbb4e6
--- /dev/null
+++ b/layout/reftests/css-grid/grid-item-overflow-stretch-001-ref.html
@@ -0,0 +1,78 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Reference: stretching overflow!=visible items</title>
+  <link rel="author" title="Mats Palmgren" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1348857">
+  <style type="text/css">
+body,html { color:black; background:white; font:16px/1 monospace; padding:0; margin:0; }
+
+.grid {
+  display: inline-grid;
+  width: 100px;
+  height: 50px;
+  grid: 7px 30px 3px / 7px 80px 3px;
+  grid-gap: 5px;
+  border:1px solid;
+}
+
+.grid > * {
+  grid-area: 2/2;
+  border:1px solid;
+  min-width:0;
+  min-height:0;
+  box-sizing: border-box;
+}
+
+.oa, .os, .oh { width:80px; height:30px; }
+.m.oa, .m.os, .m.oh { width:70px; height:24px; }
+.oa { overflow: auto; }
+.os { overflow: scroll; }
+.oh { overflow: hidden; }
+.m  { margin: 1px 3px 5px 7px; }
+
+x { display:block; width:110px; height:5px; background:grey; }
+.h .grid x { width:5px; height:110px; }
+
+br { clear:both; }
+  </style>
+</head>
+<body>
+
+<div class="grid"><span class="oa"><x></x></span></div>
+<div class="grid"><span class="os"><x></x></span></div>
+<div class="grid"><span class="oh"><x></x></span></div>
+<div class="grid"><span class="  " style="width:112px"><x></x></span></div>
+
+<br>
+
+<div class="grid"><span class="m oa"><x></x></span></div>
+<div class="grid"><span class="m os"><x></x></span></div>
+<div class="grid"><span class="m oh"><x></x></span></div>
+<div class="grid"><span class="m   " style="width:112px"><x></x></span></div>
+
+<br>
+
+<div class="h">
+
+<div class="grid"><span class="oa"><x></x></span></div>
+<div class="grid"><span class="os"><x></x></span></div>
+<div class="grid"><span class="oh"><x></x></span></div>
+<div class="grid"><span class="  " style="height:112px"><x></x></span></div>
+
+<br>
+
+<div class="grid"><span class="m oa"><x></x></span></div>
+<div class="grid"><span class="m os"><x></x></span></div>
+<div class="grid"><span class="m oh"><x></x></span></div>
+<div class="grid"><span class="m   " style="height:112px"><x></x></span></div>
+
+<br>
+
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/css-grid/grid-item-overflow-stretch-001.html b/layout/reftests/css-grid/grid-item-overflow-stretch-001.html
new file mode 100644
index 000000000..4f6259abe
--- /dev/null
+++ b/layout/reftests/css-grid/grid-item-overflow-stretch-001.html
@@ -0,0 +1,74 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: stretching overflow!=visible items</title>
+  <link rel="author" title="Mats Palmgren" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1348857">
+  <link rel="match" href="grid-item-overflow-stretch-001-ref.html">
+  <style type="text/css">
+body,html { color:black; background:white; font:16px/1 monospace; padding:0; margin:0; }
+
+.grid {
+  display: inline-grid;
+  width: 100px;
+  height: 50px;
+  grid: 7px auto 3px / 7px auto 3px;
+  grid-gap: 5px;
+  border:1px solid;
+}
+
+.grid > * {
+  grid-area: 2/2;
+  border:1px solid;
+}
+
+.oa { overflow: auto; }
+.os { overflow: scroll; }
+.oh { overflow: hidden; }
+.m  { margin: 1px 3px 5px 7px; }
+
+x { display:block; width:110px; height:5px; background:grey; }
+.h .grid x { width:5px; height:110px; }
+
+br { clear:both; }
+  </style>
+</head>
+<body>
+
+<div class="grid"><span class="oa"><x></x></span></div>
+<div class="grid"><span class="os"><x></x></span></div>
+<div class="grid"><span class="oh"><x></x></span></div>
+<div class="grid"><span class="  "><x></x></span></div>
+
+<br>
+
+<div class="grid"><span class="m oa"><x></x></span></div>
+<div class="grid"><span class="m os"><x></x></span></div>
+<div class="grid"><span class="m oh"><x></x></span></div>
+<div class="grid"><span class="m   "><x></x></span></div>
+
+<br>
+
+<div class="h">
+
+<div class="grid"><span class="oa"><x></x></span></div>
+<div class="grid"><span class="os"><x></x></span></div>
+<div class="grid"><span class="oh"><x></x></span></div>
+<div class="grid"><span class="  "><x></x></span></div>
+
+<br>
+
+<div class="grid"><span class="m oa"><x></x></span></div>
+<div class="grid"><span class="m os"><x></x></span></div>
+<div class="grid"><span class="m oh"><x></x></span></div>
+<div class="grid"><span class="m   "><x></x></span></div>
+
+<br>
+
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/css-grid/grid-item-overflow-stretch-002-ref.html b/layout/reftests/css-grid/grid-item-overflow-stretch-002-ref.html
new file mode 100644
index 000000000..a9690a54e
--- /dev/null
+++ b/layout/reftests/css-grid/grid-item-overflow-stretch-002-ref.html
@@ -0,0 +1,79 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Reference: stretching overflow!=visible vertical-rl items</title>
+  <link rel="author" title="Mats Palmgren" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1348857">
+  <style type="text/css">
+body,html { color:black; background:white; font:16px/1 monospace; padding:0; margin:0; }
+
+.grid {
+  display: inline-grid;
+  width: 100px;
+  height: 50px;
+  grid: 7px 30px 3px / 7px 80px 3px;
+  grid-gap: 5px;
+  border:1px solid;
+}
+
+.grid > * {
+  grid-area: 2/2;
+  border:1px solid;
+  writing-mode: vertical-rl;
+  min-width:0;
+  min-height:0;
+  box-sizing: border-box;
+}
+
+.oa, .os, .oh { width:80px; height:30px; }
+.m.oa, .m.os, .m.oh { width:70px; height:24px; }
+.oa { overflow: auto; }
+.os { overflow: scroll; }
+.oh { overflow: hidden; }
+.m  { margin: 1px 3px 5px 7px; }
+
+x { display:block; width:110px; height:5px; background:grey; }
+.h .grid x { width:5px; height:110px; }
+
+br { clear:both; }
+  </style>
+</head>
+<body>
+
+<div class="grid"><span class="oa"><x></x></span></div>
+<div class="grid"><span class="os"><x></x></span></div>
+<div class="grid"><span class="oh"><x></x></span></div>
+<div class="grid"><span class="  " style="width:112px"><x></x></span></div>
+
+<br>
+
+<div class="grid"><span class="m oa"><x></x></span></div>
+<div class="grid"><span class="m os"><x></x></span></div>
+<div class="grid"><span class="m oh"><x></x></span></div>
+<div class="grid"><span class="m   " style="width:112px"><x></x></span></div>
+
+<br>
+
+<div class="h">
+
+<div class="grid"><span class="oa"><x></x></span></div>
+<div class="grid"><span class="os"><x></x></span></div>
+<div class="grid"><span class="oh"><x></x></span></div>
+<div class="grid"><span class="  " style="height:112px"><x></x></span></div>
+
+<br>
+
+<div class="grid"><span class="m oa"><x></x></span></div>
+<div class="grid"><span class="m os"><x></x></span></div>
+<div class="grid"><span class="m oh"><x></x></span></div>
+<div class="grid"><span class="m   " style="height:112px"><x></x></span></div>
+
+<br>
+
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/css-grid/grid-item-overflow-stretch-002.html b/layout/reftests/css-grid/grid-item-overflow-stretch-002.html
new file mode 100644
index 000000000..520eed911
--- /dev/null
+++ b/layout/reftests/css-grid/grid-item-overflow-stretch-002.html
@@ -0,0 +1,75 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: stretching overflow!=visible vertical-rl items</title>
+  <link rel="author" title="Mats Palmgren" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1348857">
+  <link rel="match" href="grid-item-overflow-stretch-002-ref.html">
+  <style type="text/css">
+body,html { color:black; background:white; font:16px/1 monospace; padding:0; margin:0; }
+
+.grid {
+  display: inline-grid;
+  width: 100px;
+  height: 50px;
+  grid: 7px auto 3px / 7px auto 3px;
+  grid-gap: 5px;
+  border:1px solid;
+}
+
+.grid > * {
+  grid-area: 2/2;
+  border:1px solid;
+  writing-mode: vertical-rl;
+}
+
+.oa { overflow: auto; }
+.os { overflow: scroll; }
+.oh { overflow: hidden; }
+.m  { margin: 1px 3px 5px 7px; }
+
+x { display:block; width:110px; height:5px; background:grey; }
+.h .grid x { width:5px; height:110px; }
+
+br { clear:both; }
+  </style>
+</head>
+<body>
+
+<div class="grid"><span class="oa"><x></x></span></div>
+<div class="grid"><span class="os"><x></x></span></div>
+<div class="grid"><span class="oh"><x></x></span></div>
+<div class="grid"><span class="  "><x></x></span></div>
+
+<br>
+
+<div class="grid"><span class="m oa"><x></x></span></div>
+<div class="grid"><span class="m os"><x></x></span></div>
+<div class="grid"><span class="m oh"><x></x></span></div>
+<div class="grid"><span class="m   "><x></x></span></div>
+
+<br>
+
+<div class="h">
+
+<div class="grid"><span class="oa"><x></x></span></div>
+<div class="grid"><span class="os"><x></x></span></div>
+<div class="grid"><span class="oh"><x></x></span></div>
+<div class="grid"><span class="  "><x></x></span></div>
+
+<br>
+
+<div class="grid"><span class="m oa"><x></x></span></div>
+<div class="grid"><span class="m os"><x></x></span></div>
+<div class="grid"><span class="m oh"><x></x></span></div>
+<div class="grid"><span class="m   "><x></x></span></div>
+
+<br>
+
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/css-grid/grid-item-overflow-stretch-003-ref.html b/layout/reftests/css-grid/grid-item-overflow-stretch-003-ref.html
new file mode 100644
index 000000000..c082e6be4
--- /dev/null
+++ b/layout/reftests/css-grid/grid-item-overflow-stretch-003-ref.html
@@ -0,0 +1,84 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Reference: margin:auto stretch items</title>
+  <link rel="author" title="Mats Palmgren" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1348857">
+  <style type="text/css">
+body,html { color:black; background:white; font:16px/1 monospace; padding:0; margin:0; }
+
+.grid {
+  display: inline-grid;
+  width: 100px;
+  height: 50px;
+  grid: 7px 30px 3px / 7px 112px 3px;
+  grid-gap: 5px;
+  border:1px solid;
+}
+.c2 { grid-template-columns: 7px 122px 3px; }
+.h > .grid { grid: 7px 112px 3px / 7px 80px 3px; }
+
+.grid > * {
+  grid-area: 2/2;
+  border:1px solid;
+  margin: 0 auto;
+  justify-self:start;
+  align-self:start;
+  height:28px;
+}
+.c2 > * { height:22px; }
+.h .grid > * {
+  margin: 10px 0 0 10px;
+  justify-self:center;
+  align-self:center;
+  width:5px;
+  height:110px;
+}
+
+.m  { margin: 1px 3px 5px 7px; }
+
+x { display:block; width:110px; height:5px; background:grey; }
+.h .grid x { width:5px; height:110px; }
+
+br { clear:both; }
+  </style>
+</head>
+<body>
+
+<div class="grid"><span class="oa"><x></x></span></div>
+<div class="grid"><span class="os"><x></x></span></div>
+<div class="grid"><span class="oh"><x></x></span></div>
+<div class="grid"><span class="  "><x></x></span></div>
+
+<br>
+
+<div class="grid c2"><span class="m oa"><x></x></span></div>
+<div class="grid c2"><span class="m os"><x></x></span></div>
+<div class="grid c2"><span class="m oh"><x></x></span></div>
+<div class="grid c2"><span class="m   "><x></x></span></div>
+
+<br>
+
+<div class="h">
+
+<div class="grid"><span class="oa"><x></x></span></div>
+<div class="grid"><span class="os"><x></x></span></div>
+<div class="grid"><span class="oh"><x></x></span></div>
+<div class="grid"><span class="  "><x></x></span></div>
+
+<br>
+
+<div class="grid"><span class="m oa"><x></x></span></div>
+<div class="grid"><span class="m os"><x></x></span></div>
+<div class="grid"><span class="m oh"><x></x></span></div>
+<div class="grid"><span class="m   "><x></x></span></div>
+
+<br>
+
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/css-grid/grid-item-overflow-stretch-003.html b/layout/reftests/css-grid/grid-item-overflow-stretch-003.html
new file mode 100644
index 000000000..8bcd79d9b
--- /dev/null
+++ b/layout/reftests/css-grid/grid-item-overflow-stretch-003.html
@@ -0,0 +1,75 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: margin:auto stretch items</title>
+  <link rel="author" title="Mats Palmgren" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1348857">
+  <link rel="match" href="grid-item-overflow-stretch-003-ref.html">
+  <style type="text/css">
+body,html { color:black; background:white; font:16px/1 monospace; padding:0; margin:0; }
+
+.grid {
+  display: inline-grid;
+  width: 100px;
+  height: 50px;
+  grid: 7px auto 3px / 7px auto 3px;
+  grid-gap: 5px;
+  border:1px solid;
+}
+
+.grid > * {
+  grid-area: 2/2;
+  border:1px solid;
+  margin: 0 auto;
+}
+.h .grid > * {
+  margin: auto;
+}
+
+.m  { margin: 1px 3px 5px 7px; }
+
+x { display:block; width:110px; height:5px; background:grey; }
+.h .grid x { width:5px; height:110px; }
+
+br { clear:both; }
+  </style>
+</head>
+<body>
+
+<div class="grid"><span class="oa"><x></x></span></div>
+<div class="grid"><span class="os"><x></x></span></div>
+<div class="grid"><span class="oh"><x></x></span></div>
+<div class="grid"><span class="  "><x></x></span></div>
+
+<br>
+
+<div class="grid"><span class="m oa"><x></x></span></div>
+<div class="grid"><span class="m os"><x></x></span></div>
+<div class="grid"><span class="m oh"><x></x></span></div>
+<div class="grid"><span class="m   "><x></x></span></div>
+
+<br>
+
+<div class="h">
+
+<div class="grid"><span class="oa"><x></x></span></div>
+<div class="grid"><span class="os"><x></x></span></div>
+<div class="grid"><span class="oh"><x></x></span></div>
+<div class="grid"><span class="  "><x></x></span></div>
+
+<br>
+
+<div class="grid"><span class="m oa"><x></x></span></div>
+<div class="grid"><span class="m os"><x></x></span></div>
+<div class="grid"><span class="m oh"><x></x></span></div>
+<div class="grid"><span class="m   "><x></x></span></div>
+
+<br>
+
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/css-grid/grid-item-overflow-stretch-004-ref.html b/layout/reftests/css-grid/grid-item-overflow-stretch-004-ref.html
new file mode 100644
index 000000000..71ed28d7c
--- /dev/null
+++ b/layout/reftests/css-grid/grid-item-overflow-stretch-004-ref.html
@@ -0,0 +1,88 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Reference: stretching items</title>
+  <link rel="author" title="Mats Palmgren" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1348857">
+  <style type="text/css">
+body,html { color:black; background:white; font:16px/1 monospace; padding:0; margin:0; }
+
+.grid {
+  display: inline-grid;
+  width: 90px;
+  height: 50px;
+  grid: 7px 30px 3px / 7px 102px 3px;
+  grid-gap: 5px;
+  border:1px solid;
+}
+.c2 { grid: 7px 30x 3px / 7px 112px 3px; grid-gap: 5px;}
+.c3 { grid: 7px 30x 3px / 7px 70px 3px; grid-gap: 5px;}
+
+.grid > * {
+  grid-area: 2/2;
+  border:1px solid;
+  min-width: 0;
+  max-width: 100px;
+}
+.h .grid > * {
+  min-height: 0;
+  max-height: 100px;
+  justify-self:center safe;
+  align-self:center safe;
+}
+.h > .grid { grid: 7px 102px 3px / 7px 70px 3px; grid-gap: 5px;}
+.h > .grid.c2 { grid: 7px 30px 3px / 7px 70px 3px; grid-gap: 5px;}
+.h > .grid.c3 { grid: 7px 108px 3px / 7px 70px 3px; grid-gap: 5px;}
+
+.oa { overflow: auto; }
+.p { width: 100%; }
+.h .grid > .p { height: 100%; }
+.x { width:5px; }
+.h .grid > .x { max-height:5px; }
+.m { margin: 1px 3px 5px 7px; }
+
+x { display:block; width:110px; height:5px; background:grey; }
+.h .grid x { width:5px; height:110px; }
+
+br { clear:both; }
+  </style>
+</head>
+<body>
+
+<div class="grid"><span class="p oa"><x></x></span></div>
+<div class="grid"><span class="p "><x></x></span></div>
+<div class="grid c2"><span class="p x" style="height:5px; margin-left:31.5px; margin-top:11.5px"><x></x></span></div>
+<div class="grid c2"><span class="  " style="width:68px"><x></x></span></div>
+
+<br>
+
+<div class="grid c3"><span class="p m oa"><x></x></span></div>
+<div class="grid c3"><span class="p m"><x></x></span></div>
+<div class="grid c2"><span class="m p x"><x></x></span></div>
+<div class="grid c2"><span class="m " style="width:58px"><x></x></span></div>
+
+<br>
+
+<div class="h">
+
+<div class="grid"><span class="p oa"><x></x></span></div>
+<div class="grid"><span class="p "><x></x></span></div>
+<div class="grid c2"><span class="p x" style=""><x></x></span></div>
+<div class="grid c2"><span class="  " style="height:28px; width:68px;"><x></x></span></div>
+
+<br>
+
+<div class="grid c3"><span class="m p oa"><x></x></span></div>
+<div class="grid c3"><span class="m p"><x></x></span></div>
+<div class="grid c2"><span class="m p x" style="justify-self:start;align-self:start"><x></x></span></div>
+<div class="grid c2"><span class="m  " style="height:22px; width:58px"><x></x></span></div>
+
+<br>
+
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/css-grid/grid-item-overflow-stretch-004.html b/layout/reftests/css-grid/grid-item-overflow-stretch-004.html
new file mode 100644
index 000000000..b983b5184
--- /dev/null
+++ b/layout/reftests/css-grid/grid-item-overflow-stretch-004.html
@@ -0,0 +1,82 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: stretching items</title>
+  <link rel="author" title="Mats Palmgren" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1348857">
+  <link rel="match" href="grid-item-overflow-stretch-004-ref.html">
+  <style type="text/css">
+body,html { color:black; background:white; font:16px/1 monospace; padding:0; margin:0; }
+
+.grid {
+  display: inline-grid;
+  width: 90px;
+  height: 50px;
+  grid: 7px auto 3px / 7px auto 3px;
+  grid-gap: 5px;
+  border:1px solid;
+}
+
+.grid > * {
+  grid-area: 2/2;
+  border:1px solid;
+  min-width: 0;
+  max-width: 100px;
+}
+.h .grid > * {
+  min-height: 0;
+  max-height: 100px;
+}
+
+.oa { overflow: auto; }
+.p { width: 100%; }
+.h .grid > .p { height: 100%; }
+.x { max-width:5px; margin:auto; }
+.h .grid > .x { max-height:5px; }
+.m { margin: 1px 3px 5px 7px; }
+
+x { display:block; width:110px; height:5px; background:grey; }
+.h .grid x { width:5px; height:110px; }
+
+br { clear:both; }
+  </style>
+</head>
+<body>
+
+<div class="grid"><span class="p oa"><x></x></span></div>
+<div class="grid"><span class="p "><x></x></span></div>
+<div class="grid"><span class="p x"><x></x></span></div>
+<div class="grid"><span class="  "><x></x></span></div>
+
+<br>
+
+<div class="grid"><span class="p m oa"><x></x></span></div>
+<div class="grid"><span class="p m"><x></x></span></div>
+<div class="grid"><span class="m p x"><x></x></span></div>
+<div class="grid"><span class="m "><x></x></span></div>
+
+<br>
+
+<div class="h">
+
+<div class="grid"><span class="p oa"><x></x></span></div>
+<div class="grid"><span class="p "><x></x></span></div>
+<div class="grid"><span class="p x"><x></x></span></div>
+<div class="grid"><span class="  "><x></x></span></div>
+
+<br>
+
+<div class="grid"><span class="m p oa"><x></x></span></div>
+<div class="grid"><span class="m p"><x></x></span></div>
+<div class="grid"><span class="m p x"><x></x></span></div>
+<div class="grid"><span class="m  "><x></x></span></div>
+
+<br>
+
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/css-grid/grid-item-overflow-stretch-005-ref.html b/layout/reftests/css-grid/grid-item-overflow-stretch-005-ref.html
new file mode 100644
index 000000000..e7d353c8b
--- /dev/null
+++ b/layout/reftests/css-grid/grid-item-overflow-stretch-005-ref.html
@@ -0,0 +1,83 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Reference: stretching overflow!=visible items</title>
+  <link rel="author" title="Mats Palmgren" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1348857">
+  <style type="text/css">
+body,html { color:black; background:white; font:16px/1 monospace; padding:0; margin:0; }
+
+.grid {
+  display: inline-grid;
+  width: 100px;
+  height: 50px;
+  grid: 7px auto 3px / 7px auto 3px;
+  grid-gap: 5px;
+  border:1px solid;
+}
+
+.grid > * {
+  grid-area: 2/2;
+  border:1px solid;
+     -moz-appearance: none;
+  -webkit-appearance: none;
+          appearance: none;
+  min-width:0;
+  min-height:0;
+  box-sizing: border-box;
+}
+
+.oa, .os, .oh { width:80px; height:30px; }
+.m.oa, .m.os, .m.oh { width:70px; height:8px; }
+.oa { overflow: auto; }
+.os { overflow: scroll; }
+.oh { overflow: hidden; }
+.ov { justify-self: start; }
+.m.ov { align-self: start; }
+.m  { margin: 17px 3px 5px 7px; }
+
+x { display:block; width:110px; height:5px; background:grey; }
+.h .grid x { width:5px; height:110px; }
+
+br { clear:both; }
+  </style>
+</head>
+<body>
+
+<div class="grid"><input class="oa"></div>
+<div class="grid"><input class="os"></div>
+<div class="grid"><input class="oh"></div>
+<div class="grid"><input class="ov"></div>
+
+<br>
+
+<div class="grid"><input class="m oa"></div>
+<div class="grid"><input class="m os"></div>
+<div class="grid"><input class="m oh"></div>
+<div class="grid"><input class="m ov"></div>
+
+<br>
+
+<div class="h">
+
+<div class="grid"><input class="oa"></div>
+<div class="grid"><input class="os"></div>
+<div class="grid"><input class="oh"></div>
+<div class="grid"><input class="ov"></div>
+
+<br>
+
+<div class="grid"><input class="m oa"></div>
+<div class="grid"><input class="m os"></div>
+<div class="grid"><input class="m oh"></div>
+<div class="grid"><input class="m ov"></div>
+
+<br>
+
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/css-grid/grid-item-overflow-stretch-005.html b/layout/reftests/css-grid/grid-item-overflow-stretch-005.html
new file mode 100644
index 000000000..33fe468d7
--- /dev/null
+++ b/layout/reftests/css-grid/grid-item-overflow-stretch-005.html
@@ -0,0 +1,77 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: stretching overflow!=visible items</title>
+  <link rel="author" title="Mats Palmgren" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1348857">
+  <link rel="match" href="grid-item-overflow-stretch-005-ref.html">
+  <style type="text/css">
+body,html { color:black; background:white; font:16px/1 monospace; padding:0; margin:0; }
+
+.grid {
+  display: inline-grid;
+  width: 100px;
+  height: 50px;
+  grid: 7px auto 3px / 7px auto 3px;
+  grid-gap: 5px;
+  border:1px solid;
+}
+
+.grid > * {
+  grid-area: 2/2;
+  border:1px solid;
+     -moz-appearance: none;
+  -webkit-appearance: none;
+          appearance: none;
+}
+
+.oa { overflow: auto; }
+.os { overflow: scroll; }
+.oh { overflow: hidden; }
+.m  { margin: 17px 3px 5px 7px; }
+
+x { display:block; width:110px; height:5px; background:grey; }
+.h .grid x { width:5px; height:110px; }
+
+br { clear:both; }
+  </style>
+</head>
+<body>
+
+<div class="grid"><input class="oa"></div>
+<div class="grid"><input class="os"></div>
+<div class="grid"><input class="oh"></div>
+<div class="grid"><input class="  "></div>
+
+<br>
+
+<div class="grid"><input class="m oa"></div>
+<div class="grid"><input class="m os"></div>
+<div class="grid"><input class="m oh"></div>
+<div class="grid"><input class="m   "></div>
+
+<br>
+
+<div class="h">
+
+<div class="grid"><input class="oa"></div>
+<div class="grid"><input class="os"></div>
+<div class="grid"><input class="oh"></div>
+<div class="grid"><input class="  "></div>
+
+<br>
+
+<div class="grid"><input class="m oa"></div>
+<div class="grid"><input class="m os"></div>
+<div class="grid"><input class="m oh"></div>
+<div class="grid"><input class="m   "></div>
+
+<br>
+
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/css-grid/grid-item-overflow-stretch-006-ref.html b/layout/reftests/css-grid/grid-item-overflow-stretch-006-ref.html
new file mode 100644
index 000000000..71d4d4f54
--- /dev/null
+++ b/layout/reftests/css-grid/grid-item-overflow-stretch-006-ref.html
@@ -0,0 +1,54 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Reference: stretching overflow visible items</title>
+  <link rel="author" title="Mats Palmgren" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1348857">
+  <style type="text/css">
+body,html { color:black; background:white; font:16px/1 monospace; padding:0; margin:0; }
+
+.grid {
+  display: inline-flex;
+  width: 90px;
+  height: 40px;
+  padding: 7px 3px 3px 7px;
+  border: 1px solid;
+}
+
+.grid > * {
+  border: 1px solid;
+  margin: 5px;
+}
+
+.m  { margin: 6px 8px 10px 12px; }
+.ma { margin: auto; }
+
+x { display:block; width:110px; height:5px; background:grey; }
+.h .grid x { width:5px; height:110px; }
+
+br { clear:both; }
+  </style>
+</head>
+<body>
+
+<div class="grid"><span class=""><x></x></span></div>
+<div class="grid"><span class="m"><x></x></span></div>
+<div class="grid"><span class="ma" style="margin-left:5px"><x></x></span></div>
+
+<br>
+
+<div class="h">
+
+<div class="grid"><span class="" style="flex:1"><x></x></span></div>
+<div class="grid"><span class="m" style="flex:1"><x></x></span></div>
+<div class="grid"><span class="ma" style="margin-top:5px"><x></x></span></div>
+
+<br>
+
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/css-grid/grid-item-overflow-stretch-006.html b/layout/reftests/css-grid/grid-item-overflow-stretch-006.html
new file mode 100644
index 000000000..015c50fcc
--- /dev/null
+++ b/layout/reftests/css-grid/grid-item-overflow-stretch-006.html
@@ -0,0 +1,56 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: stretching overflow visible items</title>
+  <link rel="author" title="Mats Palmgren" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1348857">
+  <link rel="match" href="grid-item-overflow-stretch-006-ref.html">
+  <style type="text/css">
+body,html { color:black; background:white; font:16px/1 monospace; padding:0; margin:0; }
+
+.grid {
+  display: inline-grid;
+  width: 100px;
+  height: 50px;
+  grid: 7px minmax(20px, auto) 3px / 7px minmax(20px, auto) 3px;
+  grid-gap: 5px;
+  border: 1px solid;
+}
+
+.grid > * {
+  grid-area: 2/2;
+  border: 1px solid;
+}
+
+.m  { margin: 1px 3px 5px 7px; }
+.ma { margin: auto; }
+
+x { display:block; width:110px; height:5px; background:grey; }
+.h .grid x { width:5px; height:110px; }
+
+br { clear:both; }
+  </style>
+</head>
+<body>
+
+<div class="grid"><span class=""><x></x></span></div>
+<div class="grid"><span class="m"><x></x></span></div>
+<div class="grid"><span class="ma"><x></x></span></div>
+
+<br>
+
+<div class="h">
+
+<div class="grid"><span class=""><x></x></span></div>
+<div class="grid"><span class="m"><x></x></span></div>
+<div class="grid"><span class="ma"><x></x></span></div>
+
+<br>
+
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/css-grid/grid-min-content-min-sizing-transferred-size-004-ref.html b/layout/reftests/css-grid/grid-min-content-min-sizing-transferred-size-004-ref.html
index 5fa60b3b5..04d047b83 100644
--- a/layout/reftests/css-grid/grid-min-content-min-sizing-transferred-size-004-ref.html
+++ b/layout/reftests/css-grid/grid-min-content-min-sizing-transferred-size-004-ref.html
@@ -36,7 +36,7 @@ var rowtest = [
 "min-width:80%; max-height:20px", "min-width:50%", "margin-left: 50px; width:50%"
 ];
 var results = [
-"0/2px", "0/2px", "0/4px", "0/2px", "0/2px", "0/2px", "24px/2px", "20px/2px", "20px/2px", "24px/2px", "24px/52px"
+"0/2px", "0/2px", "0/4px", "0/2px", "0/2px", "0/2px", "12px/2px", "20px/2px", "20px/2px", "24px/2px", "312px/52px"
 ];
 var item_height = [
 "0", "0", "0", "0", "0", "0", "12px", "20px", "20px", "24px", "312px"
diff --git a/layout/reftests/css-grid/reftest.list b/layout/reftests/css-grid/reftest.list
index d85eefbd0..093e2faee 100644
--- a/layout/reftests/css-grid/reftest.list
+++ b/layout/reftests/css-grid/reftest.list
@@ -116,6 +116,12 @@ skip-if(Android) == grid-auto-min-sizing-percent-001.html grid-auto-min-sizing-p
 == grid-item-auto-min-size-clamp-005.html grid-item-auto-min-size-clamp-005-ref.html
 == grid-item-auto-min-size-clamp-006.html grid-item-auto-min-size-clamp-006-ref.html
 == grid-item-auto-min-size-clamp-007.html grid-item-auto-min-size-clamp-007-ref.html
+== grid-item-overflow-stretch-001.html grid-item-overflow-stretch-001-ref.html
+== grid-item-overflow-stretch-002.html grid-item-overflow-stretch-002-ref.html
+== grid-item-overflow-stretch-003.html grid-item-overflow-stretch-003-ref.html
+== grid-item-overflow-stretch-004.html grid-item-overflow-stretch-004-ref.html
+== grid-item-overflow-stretch-005.html grid-item-overflow-stretch-005-ref.html
+== grid-item-overflow-stretch-006.html grid-item-overflow-stretch-006-ref.html
 == grid-item-canvas-001.html grid-item-canvas-001-ref.html
 skip-if(Android) == grid-item-button-001.html grid-item-button-001-ref.html
 == grid-item-table-stretch-001.html grid-item-table-stretch-001-ref.html
diff --git a/layout/reftests/forms/display-block-baselines-1-ref.html b/layout/reftests/forms/display-block-baselines-1-ref.html
new file mode 100644
index 000000000..d01c086b5
--- /dev/null
+++ b/layout/reftests/forms/display-block-baselines-1-ref.html
@@ -0,0 +1,91 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Testcase #1 for bug 1330962</title>
+  <style type="text/css">
+@font-face {
+ src: url(../fonts/Ahem.ttf);
+ font-family: Ahem;
+}
+html,body {
+  color:black; background-color:white; font:16px/1 Ahem; padding:0; margin:0;
+}
+* { font:16px/1 Ahem; }
+
+.block { display: block; }
+.grid { display: grid; }
+
+.no-theme {
+     -moz-appearance: none;
+  -webkit-appearance: none;
+          appearance: none;
+  padding: 20px 0;
+  border: none;
+  background: white;
+}
+
+.scroll {
+  overflow-y: scroll;
+}
+
+.no-scroll {
+  overflow: visible;
+}
+
+  </style>
+</head>
+<body>
+
+<div>
+  <div style="display:inline-grid">
+    A<img class="block" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAIAAACQkWg2AAAACXBIWXMAAAsTAAALEwEAmpwYAAAAEElEQVQoz2NgGAWjYBTAAAADEAABaJFtwwAAAABJRU5ErkJggg%3D%3D">
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-grid">
+    A
+    <input type="image" class="block" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAIAAACQkWg2AAAACXBIWXMAAAsTAAALEwEAmpwYAAAAEElEQVQoz2NgGAWjYBTAAAADEAABaJFtwwAAAABJRU5ErkJggg%3D%3D">
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A<br>
+    <div style="display:inline-block"><input type="text" value="text"></div>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A<br>
+    <div style="display:inline-block"><input type="text" value="text"></div>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A<br>
+    <div style="display:inline-block"><input type="text"></div>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A<br>
+    <div style="display:inline-block"><input class="no-theme" type="text" value="text"></div>
+  </div>
+  B
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/forms/display-block-baselines-1.html b/layout/reftests/forms/display-block-baselines-1.html
new file mode 100644
index 000000000..96ebdad71
--- /dev/null
+++ b/layout/reftests/forms/display-block-baselines-1.html
@@ -0,0 +1,92 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Testcase #1 for bug 1330962</title>
+  <style type="text/css">
+@font-face {
+ src: url(../fonts/Ahem.ttf);
+ font-family: Ahem;
+}
+html,body {
+  color:black; background-color:white; font:16px/1 Ahem; padding:0; margin:0;
+}
+* { font:16px/1 Ahem; }
+
+.block { display: block; }
+.grid { display: grid; }
+
+.no-theme {
+     -moz-appearance: none;
+  -webkit-appearance: none;
+          appearance: none;
+  padding: 20px 0;
+  border: none;
+  background: white;
+}
+
+.scroll {
+  overflow-y: scroll;
+}
+
+.no-scroll {
+  overflow: visible;
+}
+
+  </style>
+</head>
+<body>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <img class="block" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAIAAACQkWg2AAAACXBIWXMAAAsTAAALEwEAmpwYAAAAEElEQVQoz2NgGAWjYBTAAAADEAABaJFtwwAAAABJRU5ErkJggg%3D%3D">
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <input type="image" class="block" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAIAAACQkWg2AAAACXBIWXMAAAsTAAALEwEAmpwYAAAAEElEQVQoz2NgGAWjYBTAAAADEAABaJFtwwAAAABJRU5ErkJggg%3D%3D">
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <input class="block" type="text" value="text">
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <input class="block scroll" type="text" value="text">
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <input class="block" type="text">
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <input class="block no-theme" type="text" value="text">
+  </div>
+  B
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/forms/display-block-baselines-2-ref.html b/layout/reftests/forms/display-block-baselines-2-ref.html
new file mode 100644
index 000000000..441a927b4
--- /dev/null
+++ b/layout/reftests/forms/display-block-baselines-2-ref.html
@@ -0,0 +1,100 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Testcase #2 for bug 1330962</title>
+  <style type="text/css">
+html,body {
+  color:black; background-color:white; font:16px/1 monospace; padding:0; margin:0;
+}
+* { font:16px/1 monospace; }
+
+.block { display: block; }
+.grid { display: grid; }
+
+.no-theme {
+     -moz-appearance: none;
+  -webkit-appearance: none;
+          appearance: none;
+  padding: 20px 0;
+  border: none;
+  background: white;
+  color: black;
+  text-align: start;
+}
+
+.scroll {
+  overflow-y: scroll;
+}
+
+.no-scroll {
+  overflow: visible;
+}
+
+  </style>
+</head>
+<body>
+
+<div>
+  <div style="display:inline-block">
+    A<div>
+    <div style="display:inline-block"><input type="button" value="button"></div></div>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A<br>
+    <div style="display:inline-block"><button>button</button></div>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A<br>
+    <div style="display:inline-block"><input class="no-theme" type="button" value="button"></div>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A<br>
+    <button class="no-theme">button-first<div style="font-size:10px">button-last</div></button>
+  </div>
+  B
+  <div class="no-theme" style="display:inline-block">button-first<div style="font-size:10px">button-last</div></div>
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A<br>
+    <button class="no-theme" style="display:inline-grid">button-first<x style="font-size:10px">button-last</x></button>
+  </div>
+  B
+  <div class="no-theme" style="display:inline-grid">button-first<x style="font-size:10px">button-last</x></div>
+</div>
+
+<div>
+  <div style="display:inline-grid">
+    A
+    <input type="checkbox" class="block" checked>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-grid">
+    A
+    <input type="radio" class="block" checked>
+  </div>
+  B
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/forms/display-block-baselines-2.html b/layout/reftests/forms/display-block-baselines-2.html
new file mode 100644
index 000000000..78253fe4c
--- /dev/null
+++ b/layout/reftests/forms/display-block-baselines-2.html
@@ -0,0 +1,100 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Testcase #2 for bug 1330962</title>
+  <style type="text/css">
+html,body {
+  color:black; background-color:white; font:16px/1 monospace; padding:0; margin:0;
+}
+* { font:16px/1 monospace; }
+
+.block { display: block; }
+.grid { display: grid; }
+
+.no-theme {
+     -moz-appearance: none;
+  -webkit-appearance: none;
+          appearance: none;
+  padding: 20px 0;
+  border: none;
+  background: white;
+  color: black;
+  text-align: start;
+}
+
+.scroll {
+  overflow-y: scroll;
+}
+
+.no-scroll {
+  overflow: visible;
+}
+
+  </style>
+</head>
+<body>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <input class="block" type="button" value="button">
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <button class="block">button</button>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <input class="block no-theme" type="button" value="button">
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <button class="block no-theme">button-first<div style="font-size:10px">button-last</div></button>
+  </div>
+  B
+  <button class="no-theme">button-first<div style="font-size:10px">button-last</div></button>
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <button class="grid no-theme">button-first<x style="font-size:10px">button-last</x></button>
+  </div>
+  B
+  <button class="no-theme" style="display:inline-grid">button-first<x style="font-size:10px">button-last</x></button>
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <input type="checkbox" class="block" checked>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <input type="radio" class="block" checked>
+  </div>
+  B
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/forms/display-block-baselines-3-ref.html b/layout/reftests/forms/display-block-baselines-3-ref.html
new file mode 100644
index 000000000..ce277b50c
--- /dev/null
+++ b/layout/reftests/forms/display-block-baselines-3-ref.html
@@ -0,0 +1,72 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Testcase #3 for bug 1330962</title>
+  <style type="text/css">
+html,body {
+  color:black; background-color:white; font:16px/1 monospace; padding:0; margin:0;
+}
+* { font:16px/1 monospace; }
+
+.block { display: block; }
+.grid { display: grid; }
+
+.no-theme {
+     -moz-appearance: none;
+  -webkit-appearance: none;
+          appearance: none;
+  padding: 20px 0;
+  border: none;
+  background: white;
+}
+
+.scroll {
+  overflow-y: scroll;
+}
+
+.no-scroll {
+  overflow: visible;
+}
+
+  </style>
+</head>
+<body>
+
+<div>
+  <div style="display:inline-grid">
+    A
+    <textarea class="block">textarea</textarea>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-grid">
+    A
+    <textarea class="block no-theme">textarea</textarea>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-grid">
+    A
+    <textarea class="block no-theme no-scroll">textarea</textarea>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A<br>
+    <div style="display:inline-block"><fieldset style="display:inline">fieldset-first<br>fieldset-last</fieldset></div>
+  </div>
+  B
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/forms/display-block-baselines-3.html b/layout/reftests/forms/display-block-baselines-3.html
new file mode 100644
index 000000000..9f3c2b110
--- /dev/null
+++ b/layout/reftests/forms/display-block-baselines-3.html
@@ -0,0 +1,73 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Testcase #3 for bug 1330962</title>
+  <style type="text/css">
+html,body {
+  color:black; background-color:white; font:16px/1 monospace; padding:0; margin:0;
+}
+* { font:16px/1 monospace; }
+
+.block { display: block; }
+.grid { display: grid; }
+
+.no-theme {
+     -moz-appearance: none;
+  -webkit-appearance: none;
+          appearance: none;
+  padding: 20px 0;
+  border: none;
+  background: white;
+}
+
+.scroll {
+  overflow-y: scroll;
+}
+
+.no-scroll {
+  overflow: visible;
+}
+
+  </style>
+</head>
+<body>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <textarea class="block">textarea</textarea>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <textarea class="block no-theme">textarea</textarea>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <textarea class="block no-theme no-scroll">textarea</textarea>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <fieldset class="block">fieldset-first<br>fieldset-last</fieldset>
+  </div>
+  B
+</div>
+
+
+</body>
+</html>
diff --git a/layout/reftests/forms/display-block-baselines-4-ref.html b/layout/reftests/forms/display-block-baselines-4-ref.html
new file mode 100644
index 000000000..5015d50c4
--- /dev/null
+++ b/layout/reftests/forms/display-block-baselines-4-ref.html
@@ -0,0 +1,73 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Testcase #4 for bug 1330962</title>
+  <style type="text/css">
+html,body {
+  color:black; background-color:white; font:16px/1 monospace; padding:0; margin:0;
+}
+* { font:16px/1 monospace; }
+
+.block { display: block; }
+.grid { display: grid; }
+
+.no-theme {
+     -moz-appearance: none;
+  -webkit-appearance: none;
+          appearance: none;
+  padding: 20px 0;
+  border: none;
+  background: white;
+}
+
+.scroll {
+  overflow-y: scroll;
+}
+
+.no-scroll {
+  overflow: visible;
+}
+
+  </style>
+</head>
+<body>
+
+<div>
+  <div style="display:inline-block">
+    A<br>
+    <div style="display:inline-block"><fieldset style="display:inline"><legend>legend</legend>
+fieldset-first<br>fieldset-last</fieldset></div>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A<br>
+    <fieldset style="display:inline-grid">grid-fieldset-first<x>grid-fieldset-last</x></fieldset>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A<br>
+    <fieldset style="display:inline" class="no-theme">fieldset-first<br>fieldset-last</fieldset>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A<br>
+    <fieldset style="display:inline" class="no-theme scroll">fieldset-first<br>fieldset-last</fieldset>
+  </div>
+  B
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/forms/display-block-baselines-4.html b/layout/reftests/forms/display-block-baselines-4.html
new file mode 100644
index 000000000..1bfd344b0
--- /dev/null
+++ b/layout/reftests/forms/display-block-baselines-4.html
@@ -0,0 +1,74 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Testcase #4 for bug 1330962</title>
+  <style type="text/css">
+html,body {
+  color:black; background-color:white; font:16px/1 monospace; padding:0; margin:0;
+}
+* { font:16px/1 monospace; }
+
+.block { display: block; }
+.grid { display: grid; }
+
+.no-theme {
+     -moz-appearance: none;
+  -webkit-appearance: none;
+          appearance: none;
+  padding: 20px 0;
+  border: none;
+  background: white;
+}
+
+.scroll {
+  overflow-y: scroll;
+}
+
+.no-scroll {
+  overflow: visible;
+}
+
+  </style>
+</head>
+<body>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <fieldset class="block"><legend>legend</legend>
+fieldset-first<br>fieldset-last</fieldset>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <fieldset class="grid"><x style="order:2">grid-fieldset-last</x>grid-fieldset-first</fieldset>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <fieldset class="block no-theme">fieldset-first<br>fieldset-last</fieldset>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <fieldset class="block no-theme scroll">fieldset-first<br>fieldset-last</fieldset>
+  </div>
+  B
+</div>
+
+
+</body>
+</html>
diff --git a/layout/reftests/forms/display-block-baselines-5-ref.html b/layout/reftests/forms/display-block-baselines-5-ref.html
new file mode 100644
index 000000000..0dce47f59
--- /dev/null
+++ b/layout/reftests/forms/display-block-baselines-5-ref.html
@@ -0,0 +1,72 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Reference: Testcase #5 for bug 1330962</title>
+  <style type="text/css">
+html,body {
+  color:black; background-color:white; font:16px/1 monospace; padding:0; margin:0;
+}
+* { font:16px/1 monospace; }
+
+.block { display: block; }
+.grid { display: grid; }
+
+.no-theme {
+     -moz-appearance: none;
+  -webkit-appearance: none;
+          appearance: none;
+  padding: 20px 0;
+  border: none;
+  background: white;
+}
+
+.scroll {
+  overflow-y: scroll;
+}
+
+.no-scroll {
+  overflow: visible;
+}
+
+  </style>
+</head>
+<body>
+
+<div>
+  <div style="display:inline-block">
+    A<br>
+    <input type="color">
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A<br>
+    <input type="color" class="no-theme">
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A<br>
+    <select><option>select</select>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A<br>
+    <select class="no-theme"><option>select</select>
+  </div>
+  B
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/forms/display-block-baselines-5.html b/layout/reftests/forms/display-block-baselines-5.html
new file mode 100644
index 000000000..0359c8a6f
--- /dev/null
+++ b/layout/reftests/forms/display-block-baselines-5.html
@@ -0,0 +1,72 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>Testcase #5 for bug 1330962</title>
+  <style type="text/css">
+html,body {
+  color:black; background-color:white; font:16px/1 monospace; padding:0; margin:0;
+}
+* { font:16px/1 monospace; }
+
+.block { display: block; }
+.grid { display: grid; }
+
+.no-theme {
+     -moz-appearance: none;
+  -webkit-appearance: none;
+          appearance: none;
+  padding: 20px 0;
+  border: none;
+  background: white;
+}
+
+.scroll {
+  overflow-y: scroll;
+}
+
+.no-scroll {
+  overflow: visible;
+}
+
+  </style>
+</head>
+<body>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <input type="color" class="block">
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <input type="color" class="block no-theme">
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <select class="block"><option>select</select>
+  </div>
+  B
+</div>
+
+<div>
+  <div style="display:inline-block">
+    A
+    <select class="block no-theme"><option>select</select>
+  </div>
+  B
+</div>
+
+</body>
+</html>
diff --git a/layout/reftests/forms/reftest.list b/layout/reftests/forms/reftest.list
index d45db276f..c7532077b 100644
--- a/layout/reftests/forms/reftest.list
+++ b/layout/reftests/forms/reftest.list
@@ -1,4 +1,9 @@
 fuzzy-if(skiaContent,1,10) HTTP(..) == text-control-baseline-1.html text-control-baseline-1-ref.html
+fuzzy-if(cocoaWidget,16,64) fuzzy-if(Android,52,64) fuzzy-if(/^Windows\x20NT\x206\.1/.test(http.oscpu),104,224) fuzzy-if(/^Windows\x20NT\x206\.2/.test(http.oscpu),57,400) == display-block-baselines-1.html display-block-baselines-1-ref.html # anti-aliasing issues
+== display-block-baselines-2.html display-block-baselines-2-ref.html
+== display-block-baselines-3.html display-block-baselines-3-ref.html
+== display-block-baselines-4.html display-block-baselines-4-ref.html
+fuzzy-if(Android,4,8) == display-block-baselines-5.html display-block-baselines-5-ref.html
 
 # button element
 include button/reftest.list
diff --git a/layout/reftests/svg/radialGradient-fr-01.svg b/layout/reftests/svg/radialGradient-fr-01.svg
new file mode 100644
index 000000000..2f28d3aba
--- /dev/null
+++ b/layout/reftests/svg/radialGradient-fr-01.svg
@@ -0,0 +1,27 @@
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<svg xmlns="http://www.w3.org/2000/svg"
+     xmlns:xlink="http://www.w3.org/1999/xlink">
+  <title>Test gradient fr attribute</title>
+  <defs>
+    <radialGradient id="grad1" fr="100%">
+      <stop offset="0%" stop-color="red" />
+      <stop offset="100%" stop-color="lime" />
+    </radialGradient>
+    <radialGradient id="grad2" xlink:href="#grad1"/>
+    <style>
+      circle {
+        stroke-width: 3px;
+        stroke: lime;
+      }
+    </style>
+  </defs>
+  <rect width="100%" height="100%" fill="lime"/>
+
+  <circle cx="100" cy="100" r="50" fill="url(#grad1)" />
+
+  <circle cx="300" cy="100" r="50" fill="url(#grad2)" />
+</svg>
+
diff --git a/layout/reftests/svg/radialGradient-fr-02-ref.svg b/layout/reftests/svg/radialGradient-fr-02-ref.svg
new file mode 100644
index 000000000..c256f72a2
--- /dev/null
+++ b/layout/reftests/svg/radialGradient-fr-02-ref.svg
@@ -0,0 +1,28 @@
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<svg xmlns="http://www.w3.org/2000/svg"
+     xmlns:xlink="http://www.w3.org/1999/xlink">
+  <title>Test gradient fr attribute</title>
+  <defs>
+    <radialGradient id="grad1">
+      <stop offset="0%" stop-color="red" />
+      <stop offset="20%" stop-color="red" />
+      <stop offset="100%" stop-color="lime" />
+    </radialGradient>
+    <style>
+      .cover {
+        stroke-width: 3px;
+        stroke: lime;
+        fill: none;
+        image-rendering: optimizeSpeed;
+      }
+    </style>
+  </defs>
+  <rect width="100%" height="100%" fill="lime"/>
+
+  <circle cx="100" cy="100" r="50" fill="url(#grad1)" />
+  <circle class="cover" cx="100" cy="100" r="50" fill="none"/>
+</svg>
+
diff --git a/layout/reftests/svg/radialGradient-fr-02.svg b/layout/reftests/svg/radialGradient-fr-02.svg
new file mode 100644
index 000000000..1933203be
--- /dev/null
+++ b/layout/reftests/svg/radialGradient-fr-02.svg
@@ -0,0 +1,27 @@
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<svg xmlns="http://www.w3.org/2000/svg"
+     xmlns:xlink="http://www.w3.org/1999/xlink">
+  <title>Test gradient fr attribute</title>
+  <defs>
+    <radialGradient id="grad1" fr="10%">
+      <stop offset="0%" stop-color="red" />
+      <stop offset="100%" stop-color="lime" />
+    </radialGradient>
+    <style>
+      .cover {
+        stroke-width: 3px;
+        stroke: lime;
+        fill: none;
+        image-rendering: optimizeSpeed;
+      }
+    </style>
+  </defs>
+  <rect width="100%" height="100%" fill="lime"/>
+
+  <circle cx="100" cy="100" r="50" fill="url(#grad1)" />
+  <circle class="cover" cx="100" cy="100" r="50" />
+</svg>
+
diff --git a/layout/reftests/svg/reftest.list b/layout/reftests/svg/reftest.list
index e596feae8..520adc9e6 100644
--- a/layout/reftests/svg/reftest.list
+++ b/layout/reftests/svg/reftest.list
@@ -290,6 +290,8 @@ fuzzy-if(skiaContent,3,5) == pattern-scale-01c.svg pattern-scale-01-ref.svg
 == radialGradient-basic-02.svg pass.svg
 fuzzy-if(cocoaWidget,4,15982) fuzzy-if(winWidget,4,92) fuzzy-if(skiaContent,4,60) == radialGradient-basic-03.svg radialGradient-basic-03-ref.svg
 == radialGradient-basic-04.svg pass.svg
+== radialGradient-fr-01.svg pass.svg
+fuzzy(1,3235) fuzzy-if(winWidget,1,6704) == radialGradient-fr-02.svg radialGradient-fr-02-ref.svg
 fuzzy-if(skiaContent,1,3600) == rect-01.svg pass.svg
 == rect-02.svg pass.svg
 == rect-03.svg pass.svg
diff --git a/layout/style/nsCSSParser.cpp b/layout/style/nsCSSParser.cpp
index 1108ce5b5..b361cf0c2 100644
--- a/layout/style/nsCSSParser.cpp
+++ b/layout/style/nsCSSParser.cpp
@@ -8918,6 +8918,10 @@ CSSParserImpl::ParseGridTrackSize(nsCSSValue& aValue,
     return CSSParseResult::NotFound;
   }
   if (mToken.mIdent.LowerCaseEqualsLiteral("fit-content")) {
+    if (requireFixedSize) {
+      UngetToken();
+      return CSSParseResult::Error;
+    }
     nsCSSValue::Array* func = aValue.InitFunction(eCSSKeyword_fit_content, 1);
     if (ParseGridTrackBreadth(func->Item(1)) == CSSParseResult::Ok &&
         func->Item(1).IsLengthPercentCalcUnit() &&
@@ -10400,7 +10404,8 @@ CSSParserImpl::ParseLinearGradient(nsCSSValue& aValue,
     UngetToken();
 
     // <angle> ,
-    if (ParseSingleTokenVariant(cssGradient->mAngle, VARIANT_ANGLE, nullptr) &&
+    if (ParseSingleTokenVariant(cssGradient->mAngle,
+                                VARIANT_ANGLE_OR_ZERO, nullptr) &&
         !ExpectSymbol(',', true)) {
       SkipUntil(')');
       return false;
diff --git a/layout/style/test/property_database.js b/layout/style/test/property_database.js
index 9c69e7d10..62d413d98 100644
--- a/layout/style/test/property_database.js
+++ b/layout/style/test/property_database.js
@@ -132,6 +132,9 @@ var validGradientAndElementValues = [
   "linear-gradient(to right bottom, red, 50%, green 50%, 50%, blue)",
   "linear-gradient(to right bottom, red, 0%, green 50%, 100%, blue)",
 
+  /* Unitless 0 is valid as an <angle> */
+  "linear-gradient(0, red, blue)",
+
   "-moz-linear-gradient(red, blue)",
   "-moz-linear-gradient(red, yellow, blue)",
   "-moz-linear-gradient(red 1px, yellow 20%, blue 24em, green)",
@@ -388,10 +391,8 @@ var invalidGradientAndElementValues = [
   "-moz-linear-gradient(10 10px -45deg, red, blue) repeat",
   "-moz-linear-gradient(10px 10 -45deg, red, blue) repeat",
   "linear-gradient(red -99, yellow, green, blue 120%)",
-  /* Unitless 0 is invalid as an <angle> */
-  "-moz-linear-gradient(top left 0, red, blue)",
-  "-moz-linear-gradient(5px 5px 0, red, blue)",
-  "linear-gradient(0, red, blue)",
+  /* Unitless nonzero numbers are valid as an <angle> */
+  "linear-gradient(30, red, blue)",
   /* Invalid color, calc() or -moz-image-rect() function */
   "linear-gradient(red, rgb(0, rubbish, 0) 50%, red)",
   "linear-gradient(red, red calc(50% + rubbish), red)",
@@ -6270,6 +6271,7 @@ if (IsCSSPropertyPrefEnabled("layout.css.grid.enabled")) {
       "repeat(auto-fill,minmax(1%,auto))",
       "repeat(auto-fill,minmax(1em,min-content)) minmax(min-content,0)",
       "repeat(auto-fill,minmax(max-content,1mm))",
+      "repeat(2, fit-content(1px))",
       "fit-content(1px) 1fr",
       "[a] fit-content(calc(1px - 99%)) [b]",
       "[a] fit-content(10%) [b c] fit-content(1em)",
@@ -6314,6 +6316,8 @@ if (IsCSSPropertyPrefEnabled("layout.css.grid.enabled")) {
       "repeat(1, repeat(1, 20px))",
       "repeat(auto-fill, auto)",
       "repeat(auto-fit,auto)",
+      "repeat(auto-fill, fit-content(1px))",
+      "repeat(auto-fit, fit-content(1px))",
       "repeat(auto-fit,[])",
       "repeat(auto-fill, 0) repeat(auto-fit, 0) ",
       "repeat(auto-fit, 0) repeat(auto-fill, 0) ",
@@ -6335,6 +6339,8 @@ if (IsCSSPropertyPrefEnabled("layout.css.grid.enabled")) {
       "fit-content(-1px)",
       "fit-content(auto)",
       "fit-content(min-content)",
+      "fit-content(1px) repeat(auto-fit, 1px)",
+      "fit-content(1px) repeat(auto-fill, 1px)",
     ],
     unbalanced_values: [
       "(foo] 40px",
diff --git a/layout/svg/nsSVGGradientFrame.cpp b/layout/svg/nsSVGGradientFrame.cpp
index 217ab8c4a..2d7684f5a 100644
--- a/layout/svg/nsSVGGradientFrame.cpp
+++ b/layout/svg/nsSVGGradientFrame.cpp
@@ -623,7 +623,7 @@ nsSVGRadialGradientFrame::GradientVectorLengthIsZero()
 already_AddRefed<gfxPattern>
 nsSVGRadialGradientFrame::CreateGradient()
 {
-  float cx, cy, r, fx, fy;
+  float cx, cy, r, fx, fy, fr;
 
   cx = GetLengthValue(dom::SVGRadialGradientElement::ATTR_CX);
   cy = GetLengthValue(dom::SVGRadialGradientElement::ATTR_CY);
@@ -631,6 +631,7 @@ nsSVGRadialGradientFrame::CreateGradient()
   // If fx or fy are not set, use cx/cy instead
   fx = GetLengthValue(dom::SVGRadialGradientElement::ATTR_FX, cx);
   fy = GetLengthValue(dom::SVGRadialGradientElement::ATTR_FY, cy);
+  fr = GetLengthValue(dom::SVGRadialGradientElement::ATTR_FR);
 
   if (fx != cx || fy != cy) {
     // The focal point (fFx and fFy) must be clamped to be *inside* - not on -
@@ -651,7 +652,7 @@ nsSVGRadialGradientFrame::CreateGradient()
     }
   }
 
-  RefPtr<gfxPattern> pattern = new gfxPattern(fx, fy, 0, cx, cy, r);
+  RefPtr<gfxPattern> pattern = new gfxPattern(fx, fy, fr, cx, cy, r);
   return pattern.forget();
 }
 
diff --git a/testing/web-platform/meta/html/semantics/forms/the-label-element/label-attributes.html.ini b/testing/web-platform/meta/html/semantics/forms/the-label-element/label-attributes.html.ini
deleted file mode 100644
index e1a2e38b5..000000000
--- a/testing/web-platform/meta/html/semantics/forms/the-label-element/label-attributes.html.ini
+++ /dev/null
@@ -1,17 +0,0 @@
-[label-attributes.html]
-  type: testharness
-  [A non-control follows by a control with same ID.]
-    expected: FAIL
-
-  [A form control has multiple labels.]
-    expected: FAIL
-
-  [A form control has no label 1.]
-    expected: FAIL
-
-  [A form control has no label 2.]
-    expected: FAIL
-
-  [A form control has an implicit label.]
-    expected: FAIL
-
diff --git a/testing/web-platform/meta/html/semantics/forms/the-label-element/labelable-elements.html.ini b/testing/web-platform/meta/html/semantics/forms/the-label-element/labelable-elements.html.ini
index bfa61edb7..363324f2e 100644
--- a/testing/web-platform/meta/html/semantics/forms/the-label-element/labelable-elements.html.ini
+++ b/testing/web-platform/meta/html/semantics/forms/the-label-element/labelable-elements.html.ini
@@ -1,29 +1,7 @@
 [labelable-elements.html]
   type: testharness
-  [Check if the output element can access 'labels']
-    expected: FAIL
-
-  [Check if the progress element can access 'labels']
-    expected: FAIL
-
-  [Check if the select element can access 'labels']
-    expected: FAIL
-
-  [Check if the textarea element can access 'labels']
-    expected: FAIL
-
-  [Check if the button element can access 'labels']
-    expected: FAIL
-
-  [Check if the hidden input element can access 'labels']
-    expected: FAIL
-
-  [Check if the input element in radio state can access 'labels']
+  [Check if the keygen element is not a labelable element]
     expected: FAIL
 
   [Check if the keygen element can access 'labels']
     expected: FAIL
-
-  [Check if the meter element can access 'labels']
-    expected: FAIL
-
diff --git a/testing/web-platform/meta/old-tests/submission/Infraware/Forms/contents/Forms/button_labels.html.ini b/testing/web-platform/meta/old-tests/submission/Infraware/Forms/contents/Forms/button_labels.html.ini
deleted file mode 100644
index e4a30320e..000000000
--- a/testing/web-platform/meta/old-tests/submission/Infraware/Forms/contents/Forms/button_labels.html.ini
+++ /dev/null
@@ -1,5 +0,0 @@
-[button_labels.html]
-  type: testharness
-  [Forms]
-    expected: FAIL
-
diff --git a/testing/web-platform/meta/old-tests/submission/Infraware/Forms/contents/Forms/input_labels.html.ini b/testing/web-platform/meta/old-tests/submission/Infraware/Forms/contents/Forms/input_labels.html.ini
deleted file mode 100644
index da0fb96d7..000000000
--- a/testing/web-platform/meta/old-tests/submission/Infraware/Forms/contents/Forms/input_labels.html.ini
+++ /dev/null
@@ -1,5 +0,0 @@
-[input_labels.html]
-  type: testharness
-  [Forms]
-    expected: FAIL
-
diff --git a/testing/web-platform/meta/svg/interfaces.html.ini b/testing/web-platform/meta/svg/interfaces.html.ini
index f3f7f6b5c..1162695c8 100644
--- a/testing/web-platform/meta/svg/interfaces.html.ini
+++ b/testing/web-platform/meta/svg/interfaces.html.ini
@@ -820,12 +820,6 @@
   [SVGElement interface: linearGradient must inherit property "onsort" with the proper type (62)]
     expected: FAIL
 
-  [SVGRadialGradientElement interface: attribute fr]
-    expected: FAIL
-
-  [SVGRadialGradientElement interface: radialGradient must inherit property "fr" with the proper type (5)]
-    expected: FAIL
-
   [SVGElement interface: radialGradient must inherit property "onautocomplete" with the proper type (8)]
     expected: FAIL
 
diff --git a/testing/web-platform/tests/html/semantics/forms/the-label-element/iframe-label-attributes.html b/testing/web-platform/tests/html/semantics/forms/the-label-element/iframe-label-attributes.html
new file mode 100644
index 000000000..56b52c951
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-label-element/iframe-label-attributes.html
@@ -0,0 +1,8 @@
+<html>

+  <body>

+    <label>

+      <div id="div1"></div>

+    </label>

+    <label for="test13"></label>

+  </body>

+</html>
\ No newline at end of file
diff --git a/testing/web-platform/tests/html/semantics/forms/the-label-element/label-attributes.html b/testing/web-platform/tests/html/semantics/forms/the-label-element/label-attributes.html
index 826533e0c..2910f2c01 100644
--- a/testing/web-platform/tests/html/semantics/forms/the-label-element/label-attributes.html
+++ b/testing/web-platform/tests/html/semantics/forms/the-label-element/label-attributes.html
@@ -32,10 +32,53 @@
 
   <label id="lbl5" for="test7"></label>
   <input id="test7">
+
+  <label id="lbl7">
+    <label id="lbl8">
+      <div id="div1">
+        <input id="test8">
+      </div>
+    </label>
+  </label>
+  <div id="div2"></div>
+
+ <label id="lbl9">
+   <label id="lbl10" for="test10">
+    <div id="div3">
+      <input id="test9">
+    </div>
+  </label>
+ </label>
+ <div id="div4"><input id="test10"></div>
+
+  <label id="lbl11">
+    <object id="obj">
+      <input id="test11">
+      <input id="test12">
+    </object>
+  </label>
+  <label id="lbl12" for="test12"><div id="div5"></div></label>
+
+  <label id="lbl13">
+    <p id="p1">
+      <input id="test13">
+    </p>
+  </label>
+
+  <div id="div6">
+    <div id="div7">
+      <label id="lbl14">
+        <label id="lbl15" for="test15">
+          <input id="test14">
+        </label>
+      </label>
+    </div>
+  </div>
+  <input id="test15">
 </form>
 
 <label id="lbl6" for="test7"></label>
-
+<div id="content" style="display: none">
 <script>
 
   //control attribute
@@ -57,6 +100,7 @@
   }, "A label element not in a document can not label any element in the document.");
 
   test(function () {
+    var labels = document.getElementById("test3").labels;
     assert_equals(document.getElementById("lbl1").control, document.getElementById("test3"),
                   "The first labelable descendant of a label element should be its labeled control.");
 
@@ -64,6 +108,10 @@
     document.getElementById("lbl1").insertBefore(input, document.getElementById("test2"));
     assert_equals(document.getElementById("lbl1").control, input,
                   "The first labelable descendant of a label element in tree order should be its labeled control.");
+    assert_equals(input.labels.length, 1,
+                  "The form control has an ancestor with no explicit associated label, and is the first labelable descendant.");
+    assert_equals(labels.length, 0,
+                  "The number of labels should be 0 if it's not the first labelable descendant of a label element.");
     input.remove();
   }, "The labeled control for a label element that has no 'for' attribute is the first labelable element which is a descendant of that label element.");
 
@@ -101,6 +149,168 @@
   }, "A form control has multiple labels.");
 
   test(function () {
+    var labels = document.getElementById("test8").labels;
+    assert_true(labels instanceof NodeList,
+                "A form control's 'labels' property should be an instance of a NodeList.");
+    assert_equals(labels.length, 2,
+                  "The form control has two ancestors with no explicit associated label, and is the first labelable descendant.");
+    assert_array_equals(labels, [document.getElementById("lbl7"), document.getElementById("lbl8")],
+                        "The labels for a form control should be returned in tree order.");
+
+    document.getElementById('div2').insertBefore(document.getElementById('div1'), document.getElementById('div2').firstChild);
+    assert_equals(labels.length, 0,
+                  "The number of labels should be 0 after the labelable element is moved to outside of nested associated labels.");
+  }, "A labelable element is moved to outside of nested associated labels.");
+
+  test(function () {
+    var labels1 = document.getElementById("test9").labels;
+    var labels2 = document.getElementById("test10").labels;
+    assert_true(labels1 instanceof NodeList,
+                "A form control's 'labels' property should be an instance of a NodeList.");
+    assert_true(labels2 instanceof NodeList,
+                "A form control's 'labels' property should be an instance of a NodeList.");
+    assert_equals(labels1.length, 1,
+                  "The form control has an ancestor with no explicit associated label, and is the first labelable descendant.");
+    assert_equals(labels2.length, 1,
+                  "The number of labels associated with a form control should be the number of label elements for which it is a labeled control.");
+    assert_array_equals(labels1, [document.getElementById("lbl9")],
+                        "The labels for a form control should be returned in tree order.");
+    assert_array_equals(labels2, [document.getElementById("lbl10")],
+                        "The labels for a form control should be returned in tree order.");
+    document.getElementById('div3').insertBefore(document.getElementById('div4'), document.getElementById('div3').firstChild);
+    assert_equals(labels1.length, 0,
+                  "The number of labels should be 0 if it's not the first labelable descendant of a label element.");
+    assert_equals(labels2.length, 2,
+                  "The form control has an ancestor with an explicit associated label, and is the first labelable descendant.");
+  }, "A labelable element is moved to inside of nested associated labels.");
+
+  test(function () {
+    var labels1 = document.getElementById("test11").labels;
+    var labels2 = document.getElementById("test12").labels;
+    assert_true(labels1 instanceof NodeList,
+                "A form control's 'labels' property should be an instance of a NodeList.");
+    assert_true(labels2 instanceof NodeList,
+                "A form control's 'labels' property should be an instance of a NodeList.");
+    assert_equals(labels1.length, 1,
+                  "The form control has an ancestor with no explicit associated label, and it is the first labelable descendant.");
+    assert_equals(labels2.length, 1,
+                  "The number of labels should be 1 since there is a label with a 'for' attribute associated with this labelable element.");
+    assert_array_equals(labels1, [document.getElementById("lbl11")],
+                        "The labels for a form control should be returned in tree order.");
+    assert_array_equals(labels2, [document.getElementById("lbl12")],
+                        "The labels for a form control should be returned in tree order.");
+    document.getElementById('div5').appendChild(document.getElementById('obj'));
+    assert_equals(labels1.length, 0,
+                  "The number of labels should be 0 after the labelable element is moved to outside of associated label.");
+    assert_equals(labels2.length, 1,
+                  "The number of labels should be 1 after the labelable element is moved to outside of associated label.");
+  }, "A labelable element which is a descendant of non-labelable element is moved to outside of associated label.");
+
+  async_test(function () {
+    var labels = document.getElementById("test13").labels;
+    assert_true(labels instanceof NodeList,
+                "A form control's 'labels' property should be an instance of a NodeList.");
+    assert_equals(labels.length, 1,
+                  "The form control has an ancestor with no explicit associated label, and is the first labelable descendant.");
+    assert_array_equals(labels, [document.getElementById("lbl13")],
+                        "The labels for a form control should be returned in tree order.");
+    let iframe = document.createElement('iframe');
+
+    iframe.onload = this.step_func_done(() => {
+      iframe.contentWindow.document.getElementById("div1").appendChild(document.getElementById("p1"));
+      assert_equals(labels.length, 2,
+                    "The number of labels should be 2 after the labelable element is moved to iframe.");
+    });
+
+    iframe.setAttribute('src', 'http://web-platform.test:8000/html/semantics/forms/the-label-element/iframe-label-attributes.html');
+    document.body.appendChild(iframe);
+  }, "A labelable element is moved to iframe.");
+
+  test(function () {
+    var labels1 = document.getElementById("test14").labels;
+    var labels2 = document.getElementById("test15").labels;
+    assert_true(labels1 instanceof NodeList,
+                "A form control's 'labels' property should be an instance of a NodeList.");
+    assert_equals(labels1.length, 1,
+                  "The form control has an ancestor with no explicit associated label, and is the first labelable descendant.");
+    assert_equals(labels2.length, 1,
+                  "The number of labels associated with a form control should be the number of label elements for which it is a labeled control.");
+    assert_array_equals(labels1, [document.getElementById("lbl14")],
+                        "The labels for a form control should be returned in tree order.");
+
+    document.getElementById('div6').removeChild(document.getElementById('div7'));
+    assert_equals(labels1.length, 0,
+                  "The number of labels should be 0 after the labelable element is removed.");
+    assert_equals(labels2.length, 0,
+                  "The number of labels should be 0 since there is no label with a 'for' attribute associated with this labelable element.");
+  }, "A div element which contains labelable element is removed.");
+
+  test(function () {
+    // <label><input id="test16"><label for="test16"></label></label>
+    var label1 = document.createElement('label');
+    label1.innerHTML = "<input id='test16'>";
+    var label2 = document.createElement('label');
+    label2.htmlFor = "test16";
+    label1.appendChild(label2);
+
+    var input = label1.firstChild;
+    var labels = input.labels;
+
+    assert_equals(labels.length, 2,
+                  "The number of labels associated with a form control should be the number of label elements for which it is a labeled control.");
+    assert_true(labels instanceof NodeList,
+                "A form control's 'labels' property should be an instance of a NodeList.");
+    assert_equals(label1.control, input, "The first labelable descendant of a label element should be its labeled control.");
+    assert_equals(label2.control, input, "The labeled cotrol should be associated with the control whose ID is equal to the value of the 'for' attribute.");
+  }, "A labelable element not in a document can label element in the same tree.");
+
+  test(function () {
+    var isShadowDOMV0;
+    if ("createShadowRoot" in document.getElementById('content')) {
+      isShadowDOMV0 = true;
+    }
+    var root1;
+    if (isShadowDOMV0) {
+      root1 = document.getElementById('content').createShadowRoot();
+    } else {
+      root1 = document.getElementById('content').attachShadow({mode: 'open'});
+    }
+    assert_true(root1 instanceof DocumentFragment,
+                "ShadowRoot should be an instance of DocumentFragment.");
+    // <label><input id="shadow1"/></label><div id="div1"></div>
+    var label1 = document.createElement('label');
+    var input1 = document.createElement('input');
+    input1.setAttribute("id", "shadow1");
+    label1.appendChild(input1);
+    root1.appendChild(label1);
+
+    var div1 = document.createElement('div');
+    label1.appendChild(div1);
+    // <label for="shadow2"></label><input id="shadow2"/>
+    var root2;
+    if (isShadowDOMV0) {
+      root2 = div1.createShadowRoot();
+    } else {
+      root2 = div1.attachShadow({mode: 'open'});
+    }
+
+    assert_true(root2 instanceof DocumentFragment,
+                "ShadowRoot should be an instance of DocumentFragment.");
+    var label2 = document.createElement('label');
+    label2.setAttribute("for", "shadow2");
+
+    var input2 = document.createElement('input');
+    input2.setAttribute("id", "shadow2");
+    root2.appendChild(label2);
+    root2.appendChild(input2);
+
+    assert_equals(root1.getElementById("shadow1").labels.length, 1,
+                  "The form control has an ancestor with no explicit associated label, and it is the first labelable descendant.");
+    assert_equals(root2.getElementById("shadow2").labels.length, 1,
+                  "The number of labels should be 1 since there is a label with a 'for' attribute associated with this labelable element.");
+  }, "A labelable element inside the shadow DOM.");
+
+  test(function () {
     var labels = document.getElementById("test3").labels;
     assert_true(labels instanceof NodeList, "A form control's 'labels' property should be an instance of a NodeList.");
     assert_equals(labels.length, 1, "The form control has an ancestor with no explicit associated label, and is the first labelable descendant.");
diff --git a/testing/web-platform/tests/page-visibility/idlharness.html b/testing/web-platform/tests/page-visibility/idlharness.html
index c8086a1bc..257546080 100644
--- a/testing/web-platform/tests/page-visibility/idlharness.html
+++ b/testing/web-platform/tests/page-visibility/idlharness.html
@@ -4,7 +4,7 @@
 <meta charset="utf-8">
 <title>Page Visibility IDL tests</title>
 <link rel="author" title="W3C" href="http://www.w3.org/" />
-<link rel="help" href="http://www.w3.org/TR/page-visibility/#sec-document-interface"/>
+<link rel="help" href="https://w3c.github.io/page-visibility/"/>
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <script src="/resources/WebIDLParser.js"></script>
@@ -16,6 +16,10 @@
 <pre id='untested_idl' style='display:none'>
 interface Document {
 };
+
+[TreatNonObjectAsNull]
+callback EventHandlerNonNull = any (Event event);
+typedef EventHandlerNonNull? EventHandler;
 </pre>
 
 <pre id='idl'>
diff --git a/widget/EventMessageList.h b/widget/EventMessageList.h
index 55fc7375e..7fe642637 100644
--- a/widget/EventMessageList.h
+++ b/widget/EventMessageList.h
@@ -448,6 +448,9 @@ NS_EVENT_MESSAGE(eEditorInput)
 NS_EVENT_MESSAGE(eSelectStart)
 NS_EVENT_MESSAGE(eSelectionChange)
 
+// visibility change
+NS_EVENT_MESSAGE(eVisibilityChange)
+
 // Details element events.
 NS_EVENT_MESSAGE(eToggle)