Fix broken hyperlink to Mozilla's list of valid composite operations in DisplayProps's documentation

Author: herebefrogs

src/easeljs/geom/DisplayProps.js

@@ -66,7 +66,7 @@ this.createjs = this.createjs||{};
 		/**
 		 * Property representing the compositeOperation that will be applied to a display object.
 		 * You can find a list of valid composite operations at:
-		 * <a href="https://developer.mozilla.org/en/Canvas_tutorial/Compositing">https://developer.mozilla.org/en/Canvas_tutorial/Compositing</a>
+		 * <a href="https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Tutorial/Compositing">https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Tutorial/Compositing</a>
 		 * @property compositeOperation
 		 * @type String
 		 **/