Separate @viewport from other RuleSet construction.

third_party/WebKit/Source/core/dom/StyleEngine.h

Index: third_party/WebKit/Source/core/dom/StyleEngine.h
diff --git a/third_party/WebKit/Source/core/dom/StyleEngine.h b/third_party/WebKit/Source/core/dom/StyleEngine.h
index 9d4e6a4c96581dfe2a76e7e6506904acd264e1c8..ca4160f3a6dbdf5bc2cd80a27622236ba81be7df 100644
--- a/third_party/WebKit/Source/core/dom/StyleEngine.h
+++ b/third_party/WebKit/Source/core/dom/StyleEngine.h
@@ -57,6 +57,7 @@ class ShadowTreeStyleSheetCollection;
 class StyleRuleFontFace;
 class StyleSheet;
 class StyleSheetContents;
+class ViewportStyleResolver;
 
 class CORE_EXPORT StyleEngine final
     : public GarbageCollectedFinalized<StyleEngine>,
@@ -99,6 +100,7 @@ class CORE_EXPORT StyleEngine final
   void removeStyleSheetCandidateNode(Node&, TreeScope&);
   void modifiedStyleSheetCandidateNode(Node&);
   void watchedSelectorsChanged();
+  void initialViewportChanged();
 
   void injectAuthorSheet(StyleSheetContents* authorSheet);
   CSSStyleSheet& ensureInspectorStyleSheet();
@@ -106,6 +108,7 @@ class CORE_EXPORT StyleEngine final
   void clearMediaQueryRuleSetStyleSheets();
   void updateStyleSheetsInImport(DocumentStyleSheetCollector& parentCollector);
   void updateActiveStyleSheets(StyleResolverUpdateMode);
+  void updateViewport() { documentStyleSheetCollection().updateViewport(); }
 
   enum ActiveSheetsUpdate { DontUpdateActiveSheets, UpdateActiveSheets };
   String preferredStylesheetSetName() const {
@@ -160,6 +163,7 @@ class CORE_EXPORT StyleEngine final
     if (!m_resolver) {
       createResolver();
     } else if (m_resolver->hasPendingAuthorStyleSheets()) {
+      updateViewport();
       m_resolver->appendPendingAuthorStyleSheets();
     }
     return *m_resolver.get();
@@ -179,6 +183,8 @@ class CORE_EXPORT StyleEngine final
   // updateGenericFontFamilySettings is used from WebSettingsImpl.
   void updateGenericFontFamilySettings();
 
+  ViewportStyleResolver& ensureViewportStyleResolver();
+
   void didDetach();
   bool shouldClearResolver() const;
   void resolverChanged(StyleResolverUpdateMode);
@@ -312,6 +318,7 @@ class CORE_EXPORT StyleEngine final
   bool m_didCalculateResolver = false;
 
   Member<StyleResolver> m_resolver;
+  Member<ViewportStyleResolver> m_viewportResolver;
   StyleInvalidator m_styleInvalidator;
 
   Member<CSSFontSelector> m_fontSelector;