Added culling sample.

samples/o3d-webgl/bitmap.js

 /*
  * Copyright 2010, 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 64 matching lines @@
 
 /**
  * The scratch canvas object.
  * @private
  */
 o3d.Bitmap.scratch_canvas_ = null;
 
 
 /**
  * Gets a canvas to use for scratch work.
+ * @return {Canvas} The canvas.
  * @private
  */
 o3d.Bitmap.getScratchCanvas_ = function() {
   if (!o3d.Bitmap.scratch_canvas_)
     o3d.Bitmap.scratch_canvas_ = document.createElement('CANVAS');
   return o3d.Bitmap.scratch_canvas_;
 }
 
 
 /**
@@ skipping 96 matching lines @@
 
 
 /**
  * The Semantic of the bitmap.
  * @type {!o3d.Bitmap.Semantic}
  */
 o3d.Bitmap.prototype.semantic = o3d.Bitmap.UNKNOWN_SEMANTIC;