Return reference from styleEngine() accessor.

Source/web/tests/WebDocumentTest.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 "public/web/WebDocument.h"
 
 #include "core/CSSPropertyNames.h"
 #include "core/dom/NodeLayoutStyle.h"
@@ skipping 17 matching lines @@
 {
     WebViewHelper webViewHelper;
     webViewHelper.initializeAndLoad("about:blank");
 
     WebDocument webDoc = webViewHelper.webView()->mainFrame()->document();
     Document* coreDoc = toLocalFrame(webViewHelper.webViewImpl()->page()->mainFrame())->document();
 
     webDoc.insertStyleSheet("body { color: green }");
 
     // Check insertStyleSheet did not cause a synchronous style recalc.
-    unsigned accessCount = coreDoc->styleEngine()->resolverAccessCount();
+    unsigned accessCount = coreDoc->styleEngine().resolverAccessCount();
     ASSERT_EQ(0U, accessCount);
 
     HTMLElement* bodyElement = coreDoc->body();
     ASSERT(bodyElement);
 
     LayoutStyle* style = bodyElement->layoutStyle();
     ASSERT(style);
 
     // Inserted stylesheet not yet applied.
     ASSERT_EQ(Color(0, 0, 0), style->visitedDependentColor(CSSPropertyColor));
@@ skipping 151 matching lines @@
     ASSERT_FALSE(coreDoc->isTransitionDocument());
 
     frame->document().setIsTransitionDocument(true);
     ASSERT_TRUE(coreDoc->isTransitionDocument());
 
     frame->document().setIsTransitionDocument(false);
     ASSERT_FALSE(coreDoc->isTransitionDocument());
 }
 
 }