Plumb in flag to enable antialiased clipping in HTML 5 Canvas

Source/platform/graphics/GraphicsContext.h

 /*
  * Copyright (C) 2003, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008-2009 Torch Mobile, Inc.
  * Copyright (C) 2013 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 304 matching lines @@
     void clipRoundedRect(const RoundedRect&, SkRegion::Op = SkRegion::kIntersect_Op);
     void clipOut(const IntRect& rect) { clipRect(rect, NotAntiAliased, SkRegion::kDifference_Op); }
     void clipOut(const Path&);
     void clipOutRoundedRect(const RoundedRect&);
     void clipPath(const Path&, WindRule = RULE_EVENODD);
     void clipConvexPolygon(size_t numPoints, const FloatPoint*, bool antialias = true);
     void clipRect(const SkRect&, AntiAliasingMode = NotAntiAliased, SkRegion::Op = SkRegion::kIntersect_Op);
     // This clip function is used only by <canvas> code. It allows
     // implementations to handle clipping on the canvas differently since
     // the discipline is different.
-    void canvasClip(const Path&, WindRule = RULE_EVENODD);
+    void canvasClip(const Path&, WindRule = RULE_EVENODD, AntiAliasingMode = NotAntiAliased);
 
     void drawText(const Font&, const TextRunPaintInfo&, const FloatPoint&);
     void drawEmphasisMarks(const Font&, const TextRunPaintInfo&, const AtomicString& mark, const FloatPoint&);
     void drawBidiText(const Font&, const TextRunPaintInfo&, const FloatPoint&, Font::CustomFontNotReadyAction = Font::DoNotPaintIfFontNotReady);
     void drawHighlightForText(const Font&, const TextRun&, const FloatPoint&, int h, const Color& backgroundColor, int from = 0, int to = -1);
 
     void drawLineForText(const FloatPoint&, float width, bool printing);
     enum DocumentMarkerLineStyle {
         DocumentMarkerSpellingLineStyle,
         DocumentMarkerGrammarLineStyle
@@ skipping 205 matching lines @@
     bool m_accelerated : 1;
     bool m_isCertainlyOpaque : 1;
     bool m_printing : 1;
     bool m_antialiasHairlineImages : 1;
     bool m_shouldSmoothFonts : 1;
 };
 
 } // namespace blink
 
 #endif // GraphicsContext_h