Bug 1371955: Diff against the correct style, not the table wrapper style. r=heycam

MozReview-Commit-ID: 9fwt2D7vOpW

--HG--
extra : rebase_source : be1e23d1d56d7c8b21529358801e903ff8aff899

layout/base/ServoRestyleManager.cpp

@@ -519,20 +519,21 @@ ServoRestyleManager::SnapshotFor(Element* aElement)
 }
 
 /* static */ nsIFrame*
-ServoRestyleManager::FrameForPseudoElement(const nsIContent* aContent,
+ServoRestyleManager::FrameForPseudoElement(const Element* aElement,
                                            nsIAtom* aPseudoTagOrNull)
 {
-  MOZ_ASSERT(!aPseudoTagOrNull || aContent->IsElement());
   if (!aPseudoTagOrNull) {
-    return aContent->GetPrimaryFrame();
+    return nsLayoutUtils::GetStyleFrame(aElement);
   }
 
   if (aPseudoTagOrNull == nsCSSPseudoElements::before) {
-    return nsLayoutUtils::GetBeforeFrame(aContent);
+    Element* pseudoElement = nsLayoutUtils::GetBeforePseudo(aElement);
+    return pseudoElement ? nsLayoutUtils::GetStyleFrame(pseudoElement) : nullptr;
   }
 
   if (aPseudoTagOrNull == nsCSSPseudoElements::after) {
-    return nsLayoutUtils::GetAfterFrame(aContent);
+    Element* pseudoElement = nsLayoutUtils::GetAfterPseudo(aElement);
+    return pseudoElement ? nsLayoutUtils::GetStyleFrame(pseudoElement) : nullptr;
   }
 
   if (aPseudoTagOrNull == nsCSSPseudoElements::firstLine ||

layout/base/ServoRestyleManager.h

@@ -82,7 +82,7 @@ public:
    * Right now only supports a null tag, before or after. If the pseudo-element
    * is not null, the content needs to be an element.
    */
-  static nsIFrame* FrameForPseudoElement(const nsIContent* aContent,
+  static nsIFrame* FrameForPseudoElement(const Element* aElement,
                                          nsIAtom* aPseudoTagOrNull);
 
   /**