[test] lazily parse css style rules

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

Index: third_party/WebKit/Source/core/css/StyleRule.cpp
diff --git a/third_party/WebKit/Source/core/css/StyleRule.cpp b/third_party/WebKit/Source/core/css/StyleRule.cpp
index ffc73fe80bc83c10d6dd96c826c9646bb7d9eb7e..9e954b738e9d18ecc9443fbfc7f6a172412e31de 100644
--- a/third_party/WebKit/Source/core/css/StyleRule.cpp
+++ b/third_party/WebKit/Source/core/css/StyleRule.cpp
@@ -33,6 +33,7 @@
 #include "core/css/StyleRuleImport.h"
 #include "core/css/StyleRuleKeyframe.h"
 #include "core/css/StyleRuleNamespace.h"
+#include "core/css/parser/CSSParserImpl.h"
 
 namespace blink {
 
@@ -217,10 +218,30 @@ StyleRule::StyleRule(CSSSelectorList selectorList, StylePropertySet* properties)
     m_selectorList = std::move(selectorList);
 }
 
+const StylePropertySet& StyleRule::properties() const
+{
+    if (!m_properties) {
+        m_properties = CSSParserImpl::parseDeclarationListForLazyStyle(m_lazyTokens, *m_context);
+        m_lazyTokens.clear();
+    }
+    return *m_properties;
+}
+
+StyleRule::StyleRule(CSSSelectorList selectorList, CSSParserTokenRange block, const CSSParserContext* context)
+    : StyleRuleBase(Style)
+    , m_selectorList(std::move(selectorList))
+    , m_properties(nullptr)
+    , m_context(context)
+{
+    while (!block.atEnd()) {
+        m_lazyTokens.append(block.consume());
+    }
+}
+
 StyleRule::StyleRule(const StyleRule& o)
     : StyleRuleBase(o)
-    , m_properties(o.m_properties->mutableCopy())
     , m_selectorList(o.m_selectorList.copy())
+    , m_properties(o.properties().mutableCopy())
 {
 }
 
@@ -230,8 +251,9 @@ StyleRule::~StyleRule()
 
 MutableStylePropertySet& StyleRule::mutableProperties()
 {
-    if (!m_properties->isMutable())
-        m_properties = m_properties->mutableCopy();
+    const StylePropertySet& props = properties();
+    if (!props.isMutable())
+        m_properties = props.mutableCopy();
     return *toMutableStylePropertySet(m_properties.get());
 }