Bug 1216431 patch 3 - Cache structs that are stored with conditions on the rule node all the time, rather than only when freshly computed. r=heycam

This is another case similar to the problem fixed in bug 1209603 patch 9.

This should make things faster by caching structs on the style context
more reliably.

--HG--
extra : commitid : GdalxPoI0wr
extra : rebase_source : 103e678a237f723b386b517d478e70214a75467e

layout/style/nsRuleNode.cpp

@@ -66,6 +66,30 @@ using std::min;
 using namespace mozilla;
 using namespace mozilla::dom;
 
+void*
+nsConditionalResetStyleData::GetConditionalStyleData(nsStyleStructID aSID,
+                               nsStyleContext* aStyleContext) const
+{
+  Entry* e = static_cast<Entry*>(mEntries[aSID]);
+  MOZ_ASSERT(e, "if mConditionalBits bit is set, we must have at least one "
+                "conditional style struct");
+  do {
+    if (e->mConditions.Matches(aStyleContext)) {
+      void* data = e->mStyleStruct;
+
+      // For reset structs with conditions, we cache the data on the
+      // style context.
+      // Tell the style context that it doesn't own the data
+      aStyleContext->AddStyleBit(GetBitForSID(aSID));
+      aStyleContext->SetStyle(aSID, data);
+
+      return data;
+    }
+    e = e->mNext;
+  } while (e);
+  return nullptr;
+}
+
 #define NS_SET_IMAGE_REQUEST(method_, context_, request_)                     \
   if ((context_)->PresContext()->IsDynamic()) {                               \
     method_(request_);                                                        \

layout/style/nsRuleNode.h

@@ -164,18 +164,15 @@ struct nsConditionalResetStyleData
     if (!(mConditionalBits & GetBitForSID(aSID))) {
       return mEntries[aSID];
     }
-    Entry* e = static_cast<Entry*>(mEntries[aSID]);
-    MOZ_ASSERT(e, "if mConditionalBits bit is set, we must have at least one "
-                  "conditional style struct");
-    do {
-      if (e->mConditions.Matches(aStyleContext)) {
-        return e->mStyleStruct;
-      }
-      e = e->mNext;
-    } while (e);
-    return nullptr;
+    return GetConditionalStyleData(aSID, aStyleContext);
   }
 
+private:
+  // non-inline helper for GetStyleData
+  void* GetConditionalStyleData(nsStyleStructID aSID,
+                                nsStyleContext* aStyleContext) const;
+
+public:
   void SetStyleData(nsStyleStructID aSID, void* aStyleStruct) {
     MOZ_ASSERT(!(mConditionalBits & GetBitForSID(aSID)),
                "rule node should not have unconditional and conditional style "