Add a utility to adjust rendering quality based on rendering performance.

samples/o3djs/js_list.scons

 # Copyright 2009, 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.
 #     * Redistributions in binary form must reproduce the above
@@ skipping 27 matching lines @@
   'element.js',
   'error.js',
   'event.js',
   'fps.js',
   'io.js',
   'loader.js',
   'material.js',
   'math.js',
   'pack.js',
   'particles.js',
+  'performance.js',
   'picking.js',
   'primitives.js',
   'quaternions.js',
   'rendergraph.js',
   'scene.js',
   'serialization.js',
   'shape.js',
   'simple.js',
   'test.js',
   'util.js',
 ]
 
 Export('O3D_JS_SOURCES');