Use dictionaries for context creation attributes. Eliminate custom bindings.

Source/core/core.gypi

Index: Source/core/core.gypi
diff --git a/Source/core/core.gypi b/Source/core/core.gypi
index 0f3284253cbc608682feba3c75d54c51a900a412..40d135f9b8377ceb769bd41deba7de6c911ac02a 100644
--- a/Source/core/core.gypi
+++ b/Source/core/core.gypi
@@ -225,7 +225,6 @@
             'html/canvas/ANGLEInstancedArrays.idl',
             'html/canvas/CHROMIUMSubscribeUniform.idl',
             'html/canvas/CHROMIUMValuebuffer.idl',
-            'html/canvas/Canvas2DContextAttributes.idl',
             'html/canvas/CanvasGradient.idl',
             'html/canvas/CanvasPattern.idl',
             'html/canvas/CanvasRenderingContext2D.idl',
@@ -248,7 +247,6 @@
             'html/canvas/WebGLCompressedTextureETC1.idl',
             'html/canvas/WebGLCompressedTexturePVRTC.idl',
             'html/canvas/WebGLCompressedTextureS3TC.idl',
-            'html/canvas/WebGLContextAttributes.idl',
             'html/canvas/WebGLContextEvent.idl',
             'html/canvas/WebGLDebugRendererInfo.idl',
             'html/canvas/WebGLDebugShaders.idl',
@@ -2625,10 +2623,6 @@
             'html/canvas/CHROMIUMSubscribeUniform.h',
             'html/canvas/CHROMIUMValuebuffer.cpp',
             'html/canvas/CHROMIUMValuebuffer.h',
-            'html/canvas/Canvas2DContextAttributes.cpp',
-            'html/canvas/Canvas2DContextAttributes.h',
-            'html/canvas/CanvasContextAttributes.cpp',
-            'html/canvas/CanvasContextAttributes.h',
             'html/canvas/CanvasGradient.cpp',
             'html/canvas/CanvasGradient.h',
             'html/canvas/CanvasImageSource.h',
@@ -2642,6 +2636,8 @@
             'html/canvas/CanvasRenderingContext2D.h',
             'html/canvas/CanvasStyle.cpp',
             'html/canvas/CanvasStyle.h',
+            'html/canvas/ContextAttributeHelpers.cpp',
+            'html/canvas/ContextAttributeHelpers.h',
             'html/canvas/ClipList.cpp',
             'html/canvas/ClipList.h',
             'html/canvas/DataView.cpp',
@@ -2685,8 +2681,6 @@
             'html/canvas/WebGLCompressedTexturePVRTC.h',
             'html/canvas/WebGLCompressedTextureS3TC.cpp',
             'html/canvas/WebGLCompressedTextureS3TC.h',
-            'html/canvas/WebGLContextAttributes.cpp',
-            'html/canvas/WebGLContextAttributes.h',
             'html/canvas/WebGLContextEvent.cpp',
             'html/canvas/WebGLContextEvent.h',
             'html/canvas/WebGLContextGroup.cpp',
@@ -3405,7 +3399,10 @@
             'events/EventInit.idl',
             'frame/ScrollOptions.idl',
             'frame/ScrollToOptions.idl',
+            'html/canvas/Canvas2DContextAttributes.idl',
+            'html/canvas/CanvasContextCreationAttributes.idl',
             'html/canvas/HitRegionOptions.idl',
+            'html/canvas/WebGLContextAttributes.idl',
             'html/track/TrackEventInit.idl',
             'page/EventSourceInit.idl',
             'storage/StorageEventInit.idl',
@@ -3425,8 +3422,14 @@
             '<(blink_core_output_dir)/frame/ScrollOptions.h',
             '<(blink_core_output_dir)/frame/ScrollToOptions.cpp',
             '<(blink_core_output_dir)/frame/ScrollToOptions.h',
+            '<(blink_core_output_dir)/html/canvas/Canvas2DContextAttributes.cpp',
+            '<(blink_core_output_dir)/html/canvas/Canvas2DContextAttributes.h',
+            '<(blink_core_output_dir)/html/canvas/CanvasContextCreationAttributes.cpp',
+            '<(blink_core_output_dir)/html/canvas/CanvasContextCreationAttributes.h',
             '<(blink_core_output_dir)/html/canvas/HitRegionOptions.cpp',
             '<(blink_core_output_dir)/html/canvas/HitRegionOptions.h',
+            '<(blink_core_output_dir)/html/canvas/WebGLContextAttributes.cpp',
+            '<(blink_core_output_dir)/html/canvas/WebGLContextAttributes.h',
             '<(blink_core_output_dir)/html/track/TrackEventInit.cpp',
             '<(blink_core_output_dir)/html/track/TrackEventInit.h',
             '<(blink_core_output_dir)/page/EventSourceInit.cpp',