Fix vertex attribute pointer not updated issue

Author: pandamicro

cocos2d/core/renderer/RendererWebGL.js

@@ -684,6 +684,9 @@ return {
             this._refreshVirtualBuffers();
         }
 
+        // Reset buffer for rendering
+        context.bindBuffer(gl.ARRAY_BUFFER, null);
+
         for (i = 0, len = locCmds.length; i < len; ++i) {
             cmd = locCmds[i];
             next = locCmds[i+1];