Plumb in flag to enable antialiased clipping in HTML 5 Canvas

Source/core/html/HTMLCanvasElement.cpp

 /*
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 150 matching lines @@
     };
 
     // FIXME - The code depends on the context not going away once created, to prevent JS from
     // seeing a dangling pointer. So for now we will disallow the context from being changed
     // once it is created.
     if (type == "2d") {
         if (m_context && !m_context->is2d())
             return 0;
         if (!m_context) {
             blink::Platform::current()->histogramEnumeration("Canvas.ContextType", Context2d, ContextTypeCount);
-            m_context = CanvasRenderingContext2D::create(this, static_cast<Canvas2DContextAttributes*>(attrs), document().inQuirksMode());
+
+            bool antialiasClips = false;
+            if (document().settings() && document().settings()->antialiasedClips2dCanvasEnabled())
+                antialiasClips = true;
+
+            m_context = CanvasRenderingContext2D::create(this, static_cast<Canvas2DContextAttributes*>(attrs), document().inQuirksMode(), antialiasClips);

[Justin Novosad, 2014/10/14 14:46:43]

Me wonders if we should just pass 'this' or 'document()' to
CanvasRenderingContext2D::create so that it can extract whatever settings it
needs (quirksMode & antialias clips).

[robertphillips, 2014/10/16 13:24:18]

Done - passed in document.

             setNeedsCompositingUpdate();
         }
         return m_context.get();
     }
 
     // Accept the the provisional "experimental-webgl" or official "webgl" context ID.
     if (type == "webgl" || type == "experimental-webgl") {
         ContextType contextType = (type == "webgl") ? ContextWebgl : ContextExperimentalWebgl;
         if (!m_context) {
             blink::Platform::current()->histogramEnumeration("Canvas.ContextType", contextType, ContextTypeCount);
@@ skipping 567 matching lines @@
 {
     return !originClean();
 }
 
 FloatSize HTMLCanvasElement::sourceSize() const
 {
     return FloatSize(width(), height());
 }
 
 }