Split the CSSParserContext class out of CSSParserMode into its own file.

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

 // Copyright 2016 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 "core/css/ActiveStyleSheets.h"
 
 #include "core/css/CSSStyleSheet.h"
 #include "core/css/MediaQueryEvaluator.h"
 #include "core/css/StyleSheetContents.h"
 #include "core/css/StyleSheetList.h"
-#include "core/css/parser/CSSParserMode.h"
+#include "core/css/parser/CSSParserContext.h"
 #include "core/dom/StyleEngine.h"
 #include "core/dom/shadow/ShadowRoot.h"
 #include "core/dom/shadow/ShadowRootInit.h"
 #include "core/frame/FrameView.h"
 #include "core/html/HTMLElement.h"
 #include "core/testing/DummyPageHolder.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace blink {
 
@@ skipping 438 matching lines @@
   ActiveStyleSheetVector oldStyleSheets;
   oldStyleSheets.push_back(
       std::make_pair(cssSheet, &cssSheet->contents()->ruleSet()));
   styleEngine().applyRuleSetChanges(shadowRoot, oldStyleSheets,
                                     ActiveStyleSheetVector());
 
   EXPECT_TRUE(styleEngine().treeBoundaryCrossingScopes().isEmpty());
 }
 
 }  // namespace blink