1 files changed, 58 insertions, 7 deletions

diff --git a/layout/style/nsComputedDOMStyle.cpp b/layout/style/nsComputedDOMStyle.cpp
index bbad9c371..7ac5fa604 100644
--- a/layout/style/nsComputedDOMStyle.cpp
+++ b/layout/style/nsComputedDOMStyle.cpp
@@ -1,5 +1,4 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/* vim: set ts=8 sts=2 et sw=2 tw=80: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
@@ -640,6 +639,34 @@ nsComputedDOMStyle::SetFrameStyleContext(nsStyleContext* aContext)
   mStyleContext = aContext;
 }
 
+/**
+ * The following function checks whether we need to explicitly resolve the style
+ * again, even though we have a style context coming from the frame.
+ *
+ * This basically checks whether the style is or may be under a ::first-line or
+ * ::first-letter frame, in which case we can't return the frame style, and we
+ * need to resolve it. See bug 505515.
+ */
+static bool
+MustReresolveStyle(const nsStyleContext* aContext)
+{
+  MOZ_ASSERT(aContext);
+
+  if (aContext->HasPseudoElementData()) {
+    if (!aContext->GetPseudo() ||
+        aContext->StyleSource().IsServoComputedValues()) {
+      // TODO(emilio): When ::first-line is supported in Servo, we may want to
+      // fix this to avoid re-resolving pseudo-element styles.
+      return true;
+    }
+
+    return aContext->GetParent() &&
+           aContext->GetParent()->HasPseudoElementData();
+  }
+
+  return false;
+}
+
 void
 nsComputedDOMStyle::UpdateCurrentStyleSources(bool aNeedsLayoutFlush)
 {
@@ -692,9 +719,20 @@ nsComputedDOMStyle::UpdateCurrentStyleSources(bool aNeedsLayoutFlush)
   // XXX the !mElement->IsHTMLElement(nsGkAtoms::area)
   // check is needed due to bug 135040 (to avoid using
   // mPrimaryFrame). Remove it once that's fixed.
-  if (!mPseudo && mStyleType == eAll &&
-      !mElement->IsHTMLElement(nsGkAtoms::area)) {
-    mOuterFrame = mElement->GetPrimaryFrame();
+  if (mStyleType == eAll && !mElement->IsHTMLElement(nsGkAtoms::area)) {
+    mOuterFrame = nullptr;
+
+    if (!mPseudo) {
+      mOuterFrame = mElement->GetPrimaryFrame();
+    } else if (mPseudo == nsCSSPseudoElements::before ||
+               mPseudo == nsCSSPseudoElements::after) {
+      nsIAtom* property = mPseudo == nsCSSPseudoElements::before
+                            ? nsGkAtoms::beforePseudoProperty
+                            : nsGkAtoms::afterPseudoProperty;
+
+      auto* pseudo = static_cast<Element*>(mElement->GetProperty(property));
+      mOuterFrame = pseudo ? pseudo->GetPrimaryFrame() : nullptr;
+    }
     mInnerFrame = mOuterFrame;
     if (mOuterFrame) {
       nsIAtom* type = mOuterFrame->GetType();
@@ -713,13 +751,15 @@ nsComputedDOMStyle::UpdateCurrentStyleSources(bool aNeedsLayoutFlush)
     }
   }
 
-  if (!mStyleContext || mStyleContext->HasPseudoElementData()) {
+  if (!mStyleContext || MustReresolveStyle(mStyleContext)) {
 #ifdef DEBUG
     if (mStyleContext) {
       // We want to check that going through this path because of
       // HasPseudoElementData is rare, because it slows us down a good
       // bit.  So check that we're really inside something associated
-      // with a pseudo-element that contains elements.
+      // with a pseudo-element that contains elements.  (We also allow
+      // the element to be NAC, just in case some chrome JS calls
+      // getComputedStyle on a NAC-implemented pseudo.)
       nsStyleContext* topWithPseudoElementData = mStyleContext;
       while (topWithPseudoElementData->GetParent()->HasPseudoElementData()) {
         topWithPseudoElementData = topWithPseudoElementData->GetParent();
@@ -730,7 +770,8 @@ nsComputedDOMStyle::UpdateCurrentStyleSources(bool aNeedsLayoutFlush)
         NS_LITERAL_STRING("we should be in a pseudo-element that is expected to contain elements ("));
       assertMsg.Append(nsDependentString(pseudoAtom->GetUTF16String()));
       assertMsg.Append(')');
-      NS_ASSERTION(nsCSSPseudoElements::PseudoElementContainsElements(pseudo),
+      NS_ASSERTION(nsCSSPseudoElements::PseudoElementContainsElements(pseudo) ||
+                   mElement->IsNativeAnonymous(),
                    NS_LossyConvertUTF16toASCII(assertMsg).get());
     }
 #endif
@@ -3264,6 +3305,16 @@ nsComputedDOMStyle::DoGetScrollSnapTypeY()
   return val.forget();
 }
 
+already_AddRefed<CSSValue>

+nsComputedDOMStyle::DoGetScrollbarWidth()

+{

+  RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;

+  val->SetIdent(

+    nsCSSProps::ValueToKeywordEnum(StyleUserInterface()->mScrollbarWidth,

+                                   nsCSSProps::kScrollbarWidthKTable));

+  return val.forget();

+}
+
 already_AddRefed<CSSValue>
 nsComputedDOMStyle::GetScrollSnapPoints(const nsStyleCoord& aCoord)
 {