Adds AS2 button support; specifies button as a container

src/flash/display/SimpleButton.js

@@ -27,6 +27,15 @@ const SimpleButtonDefinition = (function () {
       this._upState = val;
     },
 
+    get _isContainer() {
+      return true;
+    },
+    _getAS2Object: function () {
+      if (!this.$as2Object) {
+        new AS2Button().$attachNativeObject(this);
+      }
+      return this.$as2Object;
+    },
     initialize: function () {
       this._downState = null;
       this._hitArea = null;