Oilpan: fix build after r367779.

third_party/WebKit/Source/core/css/CSSStyleSheetResourceTest.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/fetch/CSSStyleSheetResource.h"
 
 #include "core/css/CSSCrossfadeValue.h"
 #include "core/css/CSSImageValue.h"
 #include "core/css/CSSPrimitiveValue.h"
 #include "core/css/CSSProperty.h"
@@ skipping 60 matching lines @@
         // the image resource.
         document()->fetcher()->setAutoLoadImages(false);
 
         ResourcePtr<CSSStyleSheetResource> cssResource = CSSStyleSheetResource::createForTest(ResourceRequest(cssURL), "utf-8");
         memoryCache()->add(cssResource.get());
         cssResource->responseReceived(ResourceResponse(cssURL, "style/css", 0, nullAtom, String()), nullptr);
         cssResource->finish();
 
         RefPtrWillBeRawPtr<StyleSheetContents> contents = StyleSheetContents::create(CSSParserContext(HTMLStandardMode, nullptr));
         RefPtrWillBeRawPtr<CSSStyleSheet> sheet = CSSStyleSheet::create(contents, document());
+        EXPECT_TRUE(sheet.get());
         RefPtrWillBeRawPtr<CSSCrossfadeValue> crossfade = CSSCrossfadeValue::create(
             CSSImageValue::create(String("image"), imageURL),
             CSSImageValue::create(String("image"), imageURL),
             CSSPrimitiveValue::create(1.0, CSSPrimitiveValue::UnitType::Number));
         Vector<OwnPtr<CSSParserSelector>> selectors;
         selectors.append(adoptPtr(new CSSParserSelector()));
         selectors[0]->setMatch(CSSSelector::Id);
         selectors[0]->setValue("foo");
         CSSProperty property(CSSPropertyBackground, crossfade);
         contents->parserAppendRule(
@@ skipping 21 matching lines @@
         }
         ASSERT_TRUE(memoryCache()->isInSameLRUListForTest(cssResource.get(), imageResource.get()));
     }
     Heap::collectAllGarbage();
     // This operation should not lead to crash!
     memoryCache()->pruneAll();
 }
 
 } // namespace
 } // namespace blink