Added ERASE blend mode

Author: photonstorm

src/gameobjects/components/BlendMode.js

@@ -37,6 +37,7 @@ var BlendMode = {
      * * ADD
      * * MULTIPLY
      * * SCREEN
+     * * ERASE
      *
      * Canvas has more available depending on browser support.
      *

src/renderer/canvas/utils/GetBlendModes.js

@@ -38,6 +38,7 @@ var GetBlendModes = function ()
     output[modes.SATURATION] = (useNew) ? 'saturation' : so;
     output[modes.COLOR] = (useNew) ? 'color' : so;
     output[modes.LUMINOSITY] = (useNew) ? 'luminosity' : so;
+    output[modes.ERASE] = 'destination-out';
 
     return output;
 };