Include supertypes

[alexeagle]

eg. from javascript/closure/ui/zippy.js

 * @extends {goog.events.EventTarget}

should produce a class goog.ui.Zippy that inherits from EventTarget

[mprobst]

And of course there's both @extends and @implements.

[mprobst]

Example from other issue:

/**
 * This creates a TwoThumbSlider object.
 * @param {goog.dom.DomHelper=} opt_domHelper Optional DOM helper.
 * @constructor
 * @extends {goog.ui.SliderBase}
 */
goog.ui.TwoThumbSlider = function(opt_domHelper) {
  goog.ui.SliderBase.call(this, opt_domHelper);
};
goog.inherits(goog.ui.TwoThumbSlider, goog.ui.SliderBase);
goog.tagUnsealableClass(goog.ui.TwoThumbSlider);

[alexeagle]

fixed by 6376b18