Revert of Enable GPU Rasterization for content with any author defined viewport.

third_party/WebKit/Source/core/dom/ViewportDescription.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2012-2013 Intel Corporation. All rights reserved.
  *
@@ skipping 238 matching lines @@
     } else if (type == ViewportDescription::HandheldFriendlyMeta) {
         metaTagTypeHistogram.count(MetaHandheldFriendly);
     } else if (type == ViewportDescription::MobileOptimizedMeta) {
         metaTagTypeHistogram.count(MobileOptimizedMeta);
     }
 #endif
 }
 
 bool ViewportDescription::matchesHeuristicsForGpuRasterization() const
 {
-    return isSpecifiedByAuthor();
+    return maxWidth == Length(DeviceWidth)
+        && minZoom == 1.0
+        && minZoomIsExplicit;
 }
 
 } // namespace blink