Bug 978833 patch 8 - Call SetImmutable for declarations of @page and keyframe rules. r=heycam

This probably should have been done before, but prior to this patch
series, dynamic changes of the declarations on these rules were broken
due to rule immutability violations; now that is no longer the case, but
to benefit from that, I believe we actually need to mark the
declarations as immutable once matched so that dynamic changes will
trigger construction of a new declaration (which thus has a new
nsIStyleRule identity).

--HG--
extra : commitid : 8IsYBd67qQr

layout/style/nsAnimationManager.cpp

@@ -625,6 +625,7 @@ ResolvedStyleCache::Get(nsPresContext *aPresContext,
   // StyleAnimationValue values in AnimationPropertySegment).
   nsStyleContext *result = mCache.GetWeak(aKeyframe);
   if (!result) {
+    aKeyframe->Declaration()->SetImmutable();
     nsCOMArray<nsIStyleRule> rules;
     rules.AppendObject(aKeyframe);
     RefPtr<nsStyleContext> resultStrong = aPresContext->StyleSet()->

layout/style/nsStyleSet.cpp

@@ -1963,6 +1963,7 @@ nsStyleSet::ResolveAnonymousBoxStyle(nsIAtom* aPseudoTag,
     nsTArray<css::ImportantStyleData*> importantRules;
     PresContext()->StyleSet()->AppendPageRules(rules);
     for (uint32_t i = 0, i_end = rules.Length(); i != i_end; ++i) {
+      rules[i]->Declaration()->SetImmutable();
       ruleWalker.Forward(rules[i]);
       css::ImportantStyleData* importantRule = rules[i]->GetImportantRule();
       if (importantRule) {