Moved Node._isDisposed, Property.isDisposed & PhetioObject.phetioObje…

…ctDisposed to PhetioObject.isDisposed, see phetsims/tandem#46

js/display/Display.js

@@ -1792,7 +1792,7 @@ define( function( require ) {
    * @returns {boolean}
    */
   Display.assertSubtreeDisposed = function( node ) {
-    assert && assert( !node.isDisposed(), 'Disposed nodes should not be included in a scene graph to display.' );
+    assert && assert( !node.isDisposed, 'Disposed nodes should not be included in a scene graph to display.' );
 
     if ( assert ) {
       for ( var i = 0; i < node.children.length; i++ ) {

js/input/Input.js

@@ -1563,7 +1563,7 @@ define( function( require ) {
 
       for ( var i = trail.getLastInputEnabledIndex(); i >= 0; bubbles ? i-- : i = -1 ) {
         var target = trail.nodes[ i ];
-        if ( target.isDisposed() ) {
+        if ( target.isDisposed ) {
           continue;
         }
 

js/nodes/Image.js

@@ -959,7 +959,7 @@ define( function( require ) {
     attachImageLoadListener: function() {
       assert && assert( !this._imageLoadListenerAttached, 'Should only be attached to one thing at a time' );
 
-      if ( !this._isDisposed ) {
+      if ( !this.isDisposed ) {
         this._image.addEventListener( 'load', this._imageLoadListener );
         this._imageLoadListenerAttached = true;
       }

js/nodes/Node.js

@@ -515,21 +515,6 @@ define( function( require ) {
     // Initialize sub-components
     this._picker = new Picker( this );
 
-    // Make sure Node's prototype dispose() is called when dispose() is called, and make sure that it isn't called
-    // more than once. See https://github.com/phetsims/scenery/issues/601.
-    // @private {boolean}
-    this._isDisposed = false;
-    if ( assert ) {
-      // Wrap the prototype dispose method with a check. NOTE: We will not catch devious cases where the dispose() is
-      // overridden after the Node constructor (which may happen).
-      var protoDispose = this.dispose;
-      this.dispose = function() {
-        assert && assert( !this._isDisposed, 'This Node has already been disposed, and cannot be disposed again' );
-        protoDispose.call( this );
-        assert && assert( this._isDisposed, 'Node.dispose() call is missing from an overridden dispose method' );
-      };
-    }
-
     // @public (scenery-internal) {boolean} - There are certain specific cases (in this case due to a11y) where we need
     // to know that a node is getting removed from its parent BUT that process has not completed yet. It would be ideal
     // to not need this.
@@ -1892,7 +1877,7 @@ define( function( require ) {
       var index = _.indexOf( this._inputListeners, listener );
 
       // ensure the listener is in our list (ignore assertion for disposal, see https://github.com/phetsims/sun/issues/394)
-      assert && assert( this._isDisposed || index >= 0, 'Could not find input listener to remove' );
+      assert && assert( this.isDisposed || index >= 0, 'Could not find input listener to remove' );
       if ( index >= 0 ) {
         this._inputListeners.splice( index, 1 );
         this._picker.onRemoveInputListener();
@@ -4999,10 +4984,7 @@ define( function( require ) {
      *
      * @returns {boolean}
      */
-    isDisposed: function() {
-      return this._isDisposed;
-    },
-    get disposed() { return this.isDisposed(); },
+    get disposed() { return this.isDisposed; },
 
     /**
      * Override for extra information in the fing output (from Display.getDebugHTML()).
@@ -5147,8 +5129,6 @@ define( function( require ) {
      * @public
      */
     dispose: function() {
-      // See constructor for Node disposal checks
-      this._isDisposed = true;
 
       // remove all accessibility input listeners
       this.disposeAccessibility();
@@ -5169,7 +5149,7 @@ define( function( require ) {
      *       techniques.
      */
     disposeSubtree: function() {
-      if ( !this.isDisposed() ) {
+      if ( !this.isDisposed ) {
         // makes a copy before disposing
         var children = this.children;
 

js/nodes/Path.js

@@ -259,7 +259,7 @@ define( function( require ) {
       assert && assert( !this._invalidShapeListenerAttached, 'We do not want to have two listeners attached!' );
 
       // Do not attach shape listeners if we are disposed
-      if ( !this._isDisposed ) {
+      if ( !this.isDisposed ) {
         this._shape.onStatic( 'invalidated', this._invalidShapeListener );
         this._invalidShapeListenerAttached = true;
       }