Use dictionaries for context creation attributes. Eliminate custom bindings.

LayoutTests/fast/canvas/webgl/webgl-context-attributes-default-value.html

Index: LayoutTests/fast/canvas/webgl/webgl-context-attributes-default-value.html
diff --git a/LayoutTests/fast/canvas/webgl/webgl-context-attributes-default-value.html b/LayoutTests/fast/canvas/webgl/webgl-context-attributes-default-value.html
index faacec9cecba3b7b068a8782a4f3de0f1bbbbdfe..94e7d552761dfaec8fdd7a6535f63b1bc6f65201 100644
--- a/LayoutTests/fast/canvas/webgl/webgl-context-attributes-default-value.html
+++ b/LayoutTests/fast/canvas/webgl/webgl-context-attributes-default-value.html
@@ -5,7 +5,7 @@
 <script src="resources/webgl-test.js"></script>
 <script>
 
-  var checkAttributes = {
+  var defaultAttributes = {
     alpha : true,
     depth : true,
     stencil : false,
@@ -17,6 +17,18 @@
     failIfMajorPerformanceCaveat : false,
   };
 
+  var falseAttributes = {
+    alpha : false,
+    depth : false,
+    stencil : false,
+    // FIXME: context.getContextAttributes().antialias is always false on
+    // content shell with --dump-render-tree option. See http://crbug.com/375682
+    // antialias : true,
+    premultipliedAlpha : false,
+    preserveDrawingBuffer : false,
+    failIfMajorPerformanceCaveat : false,
+  };
+
   function testAttributes(expectedAttributes, checkValue) {
 
     if (arguments.length != 1 && arguments.length != 2)
@@ -46,15 +58,15 @@
 <script>
 
   debug("Testing default value:");
-  testAttributes(checkAttributes);
+  testAttributes(defaultAttributes);
   debug("")
 
   debug("Testing undefined value:");
-  testAttributes(checkAttributes, undefined);
+  testAttributes(defaultAttributes, undefined);
   debug("")
 
   debug("Testing null value:");
-  testAttributes(checkAttributes, null);
+  testAttributes(falseAttributes, null);
   debug("")
 
 </script>