DevTools: allow injecting CSS rules without breaking styles sidebar.

Source/core/css/parser/CSSParserImpl.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/css/parser/CSSParserImpl.h"
 
 #include "core/css/CSSKeyframesRule.h"
 #include "core/css/CSSStyleSheet.h"
 #include "core/css/StylePropertySet.h"
@@ skipping 158 matching lines @@
 {
     CSSParserImpl parser(context);
     CSSParserObserverWrapper wrapper(observer);
     parser.m_observerWrapper = &wrapper;
     CSSTokenizer::Scope scope(declaration, wrapper);
     observer.startRuleHeader(StyleRule::Style, 0);
     observer.endRuleHeader(1);
     parser.consumeDeclarationList(scope.tokenRange(), StyleRule::Style);
 }
 
-void CSSParserImpl::parseStyleSheetForInspector(const String& string, const CSSParserContext& context, CSSParserObserver& observer)
+void CSSParserImpl::parseStyleSheetForInspector(const String& string, const CSSParserContext& context, StyleSheetContents* styleSheet, CSSParserObserver& observer)
 {
-    RefPtrWillBeRawPtr<StyleSheetContents> sheet = StyleSheetContents::create(strictCSSParserContext());
-    CSSParserImpl parser(context, sheet.get());
+    CSSParserImpl parser(context, styleSheet);
     CSSParserObserverWrapper wrapper(observer);
     parser.m_observerWrapper = &wrapper;
     CSSTokenizer::Scope scope(string, wrapper);
-    parser.consumeRuleList(scope.tokenRange(), TopLevelRuleList, [](PassRefPtrWillBeRawPtr<StyleRuleBase> rule) { });
+    bool firstRuleValid = parser.consumeRuleList(scope.tokenRange(), TopLevelRuleList, [&styleSheet](PassRefPtrWillBeRawPtr<StyleRuleBase> rule) {
+        if (rule->isCharsetRule())
+            return;
+        styleSheet->parserAppendRule(rule);
+    });
+    styleSheet->setHasSyntacticallyValidCSSHeader(firstRuleValid);
 }
 
 static CSSParserImpl::AllowedRulesType computeNewAllowedRules(CSSParserImpl::AllowedRulesType allowedRules, StyleRuleBase* rule)
 {
     if (!rule || allowedRules == CSSParserImpl::KeyframeRules || allowedRules == CSSParserImpl::NoRules)
         return allowedRules;
     ASSERT(allowedRules <= CSSParserImpl::RegularRules);
     if (rule->isCharsetRule() || rule->isImportRule())
         return CSSParserImpl::AllowImportRules;
     if (rule->isNamespaceRule())
@@ skipping 523 matching lines @@
         else
             return nullptr; // Parser error, invalid value in keyframe selector
         if (range.atEnd())
             return result.release();
         if (range.consume().type() != CommaToken)
             return nullptr; // Parser error
     }
 }
 
 } // namespace blink