Promote opaque fixed position elements.

third_party/WebKit/Source/platform/testing/RuntimeEnabledFeaturesTestHelpers.h

 // 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.
 
 #ifndef RuntimeEnabledFeaturesTestHelpers_h
 #define RuntimeEnabledFeaturesTestHelpers_h
 
 #include "platform/RuntimeEnabledFeatures.h"
 #include "wtf/Assertions.h"
 
@@ skipping 13 matching lines @@
     {
         CHECK_EQ(m_enabled, getter());
         setter(m_original);
     }
 
 private:
     bool m_enabled;
     bool m_original;
 };
 
+typedef ScopedRuntimeEnabledFeatureForTest<RuntimeEnabledFeatures::compositeOpaqueFixedPositionEnabled, RuntimeEnabledFeatures::setCompositeOpaqueFixedPositionEnabled> ScopedCompositeFixedPositionForTest;
 typedef ScopedRuntimeEnabledFeatureForTest<RuntimeEnabledFeatures::compositorWorkerEnabled, RuntimeEnabledFeatures::setCompositorWorkerEnabled> ScopedCompositorWorkerForTest;
 typedef ScopedRuntimeEnabledFeatureForTest<RuntimeEnabledFeatures::rootLayerScrollingEnabled, RuntimeEnabledFeatures::setRootLayerScrollingEnabled> ScopedRootLayerScrollingForTest;
 typedef ScopedRuntimeEnabledFeatureForTest<RuntimeEnabledFeatures::slimmingPaintV2Enabled, RuntimeEnabledFeatures::setSlimmingPaintV2Enabled> ScopedSlimmingPaintV2ForTest;
 
 } // namespace blink
 
 #endif // RuntimeEnabledFeaturesTestHelpers_h