Use css-device-adapt constraining for legacy viewport tags.

Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 2973 matching lines @@
     if (view->needsLayout())
         view->layout();
 }
 
 void WebViewImpl::updatePageDefinedPageScaleConstraints(const ViewportArguments& arguments)
 {
     if (!settings()->viewportEnabled() || !isFixedLayoutModeEnabled() || !page() || !m_size.width || !m_size.height)
         return;
 
     ViewportArguments adjustedArguments = arguments;
-    if (settingsImpl()->viewportMetaLayoutSizeQuirk() && adjustedArguments.type == ViewportArguments::ViewportMeta)
-        adjustedArguments.type = ViewportArguments::ViewportMetaLayoutSizeQuirk;
-    m_pageScaleConstraintsSet.updatePageDefinedConstraints(adjustedArguments, m_size, page()->settings().layoutFallbackWidth());
+    if (settingsImpl()->viewportMetaLayoutSizeQuirk() && adjustedArguments.type == ViewportArguments::ViewportMeta) {
+        if (adjustedArguments.maxWidth.type() == ExtendToZoom)
+            adjustedArguments.maxWidth = Length(); // auto
+        adjustedArguments.minWidth = adjustedArguments.maxWidth;
+        adjustedArguments.minHeight = adjustedArguments.maxHeight;
+    }
+    m_pageScaleConstraintsSet.updatePageDefinedConstraints(adjustedArguments, m_size);
 
     if (settingsImpl()->supportDeprecatedTargetDensityDPI())
         m_pageScaleConstraintsSet.adjustPageDefinedConstraintsForAndroidWebView(adjustedArguments, m_size, page()->settings().layoutFallbackWidth(), deviceScaleFactor(), page()->settings().useWideViewport(), page()->settings().loadWithOverviewMode());
 
     WebSize layoutSize = flooredIntSize(m_pageScaleConstraintsSet.pageDefinedConstraints().layoutSize);
 
     if (page()->settings().textAutosizingEnabled() && page()->mainFrame() && layoutSize.width != fixedLayoutSize().width)
         page()->mainFrame()->document()->textAutosizer()->recalculateMultipliers();
 
     setFixedLayoutSize(layoutSize);
@@ skipping 1103 matching lines @@
     //    the initial viewport width.
     // 2. The author has disabled viewport zoom.
 
     const PageScaleConstraints& constraints = m_pageScaleConstraintsSet.pageDefinedConstraints();
 
     return fixedLayoutSize().width == m_size.width
         || (constraints.minimumScale == constraints.maximumScale && constraints.minimumScale != -1);
 }
 
 } // namespace WebKit