Current work-in-progress crbug.com/567021

third_party/WebKit/Source/core/css/RuleSet.cpp

Index: third_party/WebKit/Source/core/css/RuleSet.cpp
diff --git a/third_party/WebKit/Source/core/css/RuleSet.cpp b/third_party/WebKit/Source/core/css/RuleSet.cpp
index 2c6c9080f4436898f4e1e4a67b5ad8de5ffd959d..931efc0527f0af81cb0ade7b819fb6e4c1efd663 100644
--- a/third_party/WebKit/Source/core/css/RuleSet.cpp
+++ b/third_party/WebKit/Source/core/css/RuleSet.cpp
@@ -230,12 +230,6 @@ void RuleSet::addPageRule(StyleRulePage* rule)
     m_pageRules.append(rule);
 }
 
-void RuleSet::addViewportRule(StyleRuleViewport* rule)
-{
-    ensurePendingRules(); // So that m_viewportRules.shrinkToFit() gets called.
-    m_viewportRules.append(rule);
-}
-
 void RuleSet::addFontFaceRule(StyleRuleFontFace* rule)
 {
     ensurePendingRules(); // So that m_fontFaceRules.shrinkToFit() gets called.
@@ -272,14 +266,12 @@ void RuleSet::addChildRules(const HeapVector<Member<StyleRuleBase>>& rules, cons
             addPageRule(toStyleRulePage(rule));
         } else if (rule->isMediaRule()) {
             StyleRuleMedia* mediaRule = toStyleRuleMedia(rule);
-            if ((!mediaRule->mediaQueries() || medium.eval(mediaRule->mediaQueries(), &m_viewportDependentMediaQueryResults, &m_deviceDependentMediaQueryResults)))
+            if ((!mediaRule->mediaQueries() || medium.eval(mediaRule->mediaQueries(), &m_features.viewportDependentMediaQueryResults, &m_features.deviceDependentMediaQueryResults)))
                 addChildRules(mediaRule->childRules(), medium, addRuleFlags);
         } else if (rule->isFontFaceRule()) {
             addFontFaceRule(toStyleRuleFontFace(rule));
         } else if (rule->isKeyframesRule()) {
             addKeyframesRule(toStyleRuleKeyframes(rule));
-        } else if (rule->isViewportRule()) {
-            addViewportRule(toStyleRuleViewport(rule));
         } else if (rule->isSupportsRule() && toStyleRuleSupports(rule)->conditionIsSupported()) {
             addChildRules(toStyleRuleSupports(rule)->childRules(), medium, addRuleFlags);
         }
@@ -295,7 +287,7 @@ void RuleSet::addRulesFromSheet(StyleSheetContents* sheet, const MediaQueryEvalu
     const HeapVector<Member<StyleRuleImport>>& importRules = sheet->importRules();
     for (unsigned i = 0; i < importRules.size(); ++i) {
         StyleRuleImport* importRule = importRules[i].get();
-        if (importRule->styleSheet() && (!importRule->mediaQueries() || medium.eval(importRule->mediaQueries(), &m_viewportDependentMediaQueryResults, &m_deviceDependentMediaQueryResults)))
+        if (importRule->styleSheet() && (!importRule->mediaQueries() || medium.eval(importRule->mediaQueries(), &m_features.viewportDependentMediaQueryResults, &m_features.deviceDependentMediaQueryResults)))
             addRulesFromSheet(importRule->styleSheet(), medium, addRuleFlags);
     }
 
@@ -339,7 +331,6 @@ void RuleSet::compactRules()
     m_universalRules.shrinkToFit();
     m_shadowHostRules.shrinkToFit();
     m_pageRules.shrinkToFit();
-    m_viewportRules.shrinkToFit();
     m_fontFaceRules.shrinkToFit();
     m_keyframesRules.shrinkToFit();
     m_deepCombinatorOrShadowPseudoRules.shrinkToFit();
@@ -347,6 +338,14 @@ void RuleSet::compactRules()
     m_slottedPseudoElementRules.shrinkToFit();
 }
 
+RuleSet* RuleSet::emptyRuleSet()
+{
+    DEFINE_STATIC_LOCAL(Persistent<RuleSet>, s_emptyRuleSet, ());
+    if (!s_emptyRuleSet)
+        s_emptyRuleSet = RuleSet::create();
+    return s_emptyRuleSet;
+}
+
 DEFINE_TRACE(MinimalRuleData)
 {
     visitor->trace(m_rule);
@@ -378,14 +377,11 @@ DEFINE_TRACE(RuleSet)
     visitor->trace(m_shadowHostRules);
     visitor->trace(m_features);
     visitor->trace(m_pageRules);
-    visitor->trace(m_viewportRules);
     visitor->trace(m_fontFaceRules);
     visitor->trace(m_keyframesRules);
     visitor->trace(m_deepCombinatorOrShadowPseudoRules);
     visitor->trace(m_contentPseudoElementRules);
     visitor->trace(m_slottedPseudoElementRules);
-    visitor->trace(m_viewportDependentMediaQueryResults);
-    visitor->trace(m_deviceDependentMediaQueryResults);
     visitor->trace(m_pendingRules);
 #ifndef NDEBUG
     visitor->trace(m_allRules);