Use dictionaries for context creation attributes. Eliminate custom bindings.

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 152 matching lines @@
 void HTMLCanvasElement::setHeight(int value)
 {
     setIntegralAttribute(heightAttr, value);
 }
 
 void HTMLCanvasElement::setWidth(int value)
 {
     setIntegralAttribute(widthAttr, value);
 }
 
-CanvasRenderingContext* HTMLCanvasElement::getContext(const String& type, CanvasContextAttributes* attrs)
+void HTMLCanvasElement::getContext(const String& type, const CanvasContextCreationAttributes& attributes, CanvasRenderingContext2DOrWebGLRenderingContext& result)
 {
     // A Canvas can either be "2D" or "webgl" but never both. If you request a 2D canvas and the existing
     // context is already 2D, just return that. If the existing context is WebGL, then destroy it
     // before creating a new 2D context. Vice versa when requesting a WebGL canvas. Requesting a
     // context with any other type string will destroy any existing context.
     enum ContextType {
         // Do not change assigned numbers of existing items: add new features to the end of the list.
         Context2d = 0,
         ContextExperimentalWebgl = 2,
         ContextWebgl = 3,
         ContextTypeCount,
     };
 
     // 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 nullptr;
+            return;
         if (!m_context) {
             blink::Platform::current()->histogramEnumeration("Canvas.ContextType", Context2d, ContextTypeCount);
 
-            m_context = CanvasRenderingContext2D::create(this, static_cast<Canvas2DContextAttributes*>(attrs), document());
+            m_context = CanvasRenderingContext2D::create(this, attributes, document());
             setNeedsCompositingUpdate();
         }
-        return m_context.get();
+        result.setCanvasRenderingContext2D(static_cast<CanvasRenderingContext2D*>(m_context.get()));
+        return;
     }
 
     // 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);
-            m_context = WebGLRenderingContext::create(this, static_cast<WebGLContextAttributes*>(attrs));
+            m_context = WebGLRenderingContext::create(this, attributes);
             setNeedsCompositingUpdate();
             updateExternallyAllocatedMemory();
         } else if (!m_context->is3d()) {
             dispatchEvent(WebGLContextEvent::create(EventTypeNames::webglcontextcreationerror, false, true, "Canvas has an existing, non-WebGL context"));
-            return nullptr;
+            return;
         }
-        return m_context.get();
+        result.setWebGLRenderingContext(static_cast<WebGLRenderingContext*>(m_context.get()));
     }
 
-    return nullptr;
+    return;
 }
 
 bool HTMLCanvasElement::isPaintable() const
 {
     if (!m_context)
         return canCreateImageBuffer(size());
     return buffer();
 }
 
 void HTMLCanvasElement::didDraw(const FloatRect& rect)
@@ skipping 573 matching lines @@
 {
     return !originClean();
 }
 
 FloatSize HTMLCanvasElement::sourceSize() const
 {
     return FloatSize(width(), height());
 }
 
 }