7 files changed, 33 insertions, 27 deletions
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 3112515ff..79f6cff51 100644
--- a/dom/base/FragmentOrElement.cpp
+++ b/dom/base/FragmentOrElement.cpp
@@ -1831,7 +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/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/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
   /**