Build: Update grunt-contrib-jshint

JSON needed to be added to JSHint globals as it's not implied by the es3
setting and yet all our supported browsers have it implemented.

(cherry-picked from 1556c4661a)

src/.jshintrc

@@ -17,6 +17,7 @@
 	"wsh": true,
 
 	"globals": {
+		"JSON": false,
 		"jQuery": true,
 		"define": false,
 		"module": false,