Add hasViewportRule() flag to StyleSheetContents.

third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp

Index: third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp
diff --git a/third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp b/third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp
index df4464540a3dbd3fe6230eaffad4432169308684..35169960f5125e7b8c323284e2333e19146694fb 100644
--- a/third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp
+++ b/third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp
@@ -614,6 +614,9 @@ StyleRuleViewport* CSSParserImpl::consumeViewportRule(
     m_observerWrapper->observer().endRuleBody(endOffset);
   }
 
+  if (m_styleSheet)
+    m_styleSheet->setHasViewportRule();
+
   consumeDeclarationList(block, StyleRule::Viewport);
   return StyleRuleViewport::create(
       createStylePropertySet(m_parsedProperties, CSSViewportRuleMode));