Implement canvas color space IDL format for 2D canvas

content/test/data/gpu/pixel_canvas_display_linear-rgb.html

Index: content/test/data/gpu/pixel_canvas_display_linear-rgb.html
diff --git a/content/test/data/gpu/pixel_canvas_display_linear-rgb.html b/content/test/data/gpu/pixel_canvas_display_linear-rgb.html
index 363b1ef04c0f332c91ff618f5ce7c0ecf28cf936..9cae0de8d97d1b1ac7846653e607ad381db26aea 100644
--- a/content/test/data/gpu/pixel_canvas_display_linear-rgb.html
+++ b/content/test/data/gpu/pixel_canvas_display_linear-rgb.html
@@ -15,7 +15,7 @@ function main()
 
 function draw()
 {
-  var ctx = document.getElementById("c").getContext("2d", {colorSpace:'linear-rgb'});
+  var ctx = document.getElementById("c").getContext("2d", {colorSpace:"srgb", pixelFormat: "float16"});
   ctx.fillStyle = 'red';
   ctx.fillRect(20,20,50,50);
   ctx.fillStyle = 'green';