add a few type definitions

core/workspace_svg.js

@@ -254,6 +254,10 @@ Blockly.WorkspaceSvg.prototype.createDom = function(opt_backgroundClass) {
   // Determine if there needs to be a category tree, or a simple list of
   // blocks.  This cannot be changed later, since the UI is very different.
   if (this.options.hasCategories) {
+    /** 
+     * @type {Blockly.Toolbox}
+     * @private
+     */
     this.toolbox_ = new Blockly.Toolbox(this);
   } else if (this.options.languageTree) {
     this.addFlyout_();