Adding more type documentation.

demos/plane/plane.js

@@ -76,7 +76,7 @@ Plane.LANGUAGE_RTL = ['ar', 'fa', 'he'];
 
 /**
  * Main Blockly workspace.
- * @type Blockly.WorkspaceSvg
+ * @type {Blockly.WorkspaceSvg}
  */
 Plane.workspace = null;
 
@@ -201,7 +201,7 @@ Plane.getMsg = function(key) {
 
 /**
  * User's language (e.g. "en").
- * @type string
+ * @type {string}
  */
 Plane.LANG = Plane.getLang();
 

demos/plane/slider.js

@@ -30,7 +30,7 @@
  * @param {number} y The vertical offset of the slider.
  * @param {number} width The total width of the slider.
  * @param {!Element} svgParent The SVG element to append the slider to.
- * @param {Function} opt_changeFunc Optional callback function that will be
+ * @param {Function=} opt_changeFunc Optional callback function that will be
  *     called when the slider is moved.  The current value is passed.
  * @constructor
  */