Bug 559491. If a visited style context has no parent then add it to the list of roots. r=dbaron

layout/style/nsStyleContext.cpp

@@ -589,9 +589,6 @@ nsStyleContext::CalcStyleDifference(nsStyleContext* aOther)
 void
 nsStyleContext::Mark()
 {
-  if (mStyleIfVisited)
-    mStyleIfVisited->Mark();
-
   // Mark our rule node.
   mRuleNode->Mark();
 

layout/style/nsStyleSet.cpp

@@ -500,6 +500,9 @@ nsStyleSet::GetContext(nsStyleContext* aParentContext,
       if (!resultIfVisited) {
         return nsnull;
       }
+      if (!parentIfVisited) {
+        mRoots.AppendElement(resultIfVisited);
+      }
       resultIfVisited->SetIsStyleIfVisited();
       result->SetStyleIfVisited(resultIfVisited.forget());