Zero-out Canvas CSS transform when the fit is set back to full displa…

…y. See #511 and phetsims/pendulum-lab#126

js/display/CanvasBlock.js

@@ -79,6 +79,7 @@ define( function( require ) {
       this.canvas.style.height = size.height + 'px';
       this.wrapper.resetStyles();
       this.canvasDrawOffset.setXY( 0, 0 );
+      Util.unsetTransform( this.canvas );
     },
 
     setSizeFitBounds: function() {