Update DisplayObject.js

`Phaser.RenderTexture` needs a reference to game as the first parameter

Author: tengbao

v2-community/src/pixi/display/DisplayObject.js

@@ -426,7 +426,7 @@ PIXI.DisplayObject.prototype = {
 
         var bounds = this.getLocalBounds();
 
-        var renderTexture = new Phaser.RenderTexture(bounds.width | 0, bounds.height | 0, renderer, scaleMode, resolution);
+        var renderTexture = new Phaser.RenderTexture(null, bounds.width | 0, bounds.height | 0, renderer, scaleMode, resolution);
 
         PIXI.DisplayObject._tempMatrix.tx = -bounds.x;
         PIXI.DisplayObject._tempMatrix.ty = -bounds.y;