Use JSON.parse instead of deprecated goog.json.parse.

Thanks to [] shared libraries at Google now produce valid JSON which allows using JSON.parse. It is safer and faster than goog.json.parse which uses eval by default.

NOTE: All shared libraries producing JSON at Google were changed to produce valid JSON. However, if your code uses a custom way of producing JSON (not using the shared libraries) or if your code parses JSON generated a long time ago and stored, this CL might break you so please review with care.

Design doc: []

Tested:
    TAP --sample for global presubmit queue
    []

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=166454709

java/google/registry/ui/js/registrar/brainframe.js

@@ -123,7 +123,7 @@ registry.registrar.BrainFrame.prototype.onMessage_ = function(e) {
     throw new Error(
         'Message origin is "' + msg.origin + '" but wanted: ' + this.origin_);
   }
-  var data = goog.json.parse(msg.data);
+  var data = /** @type {!Object} */ (JSON.parse(msg.data));
   switch (goog.object.get(data, 'type')) {
     case registry.registrar.BrainFrame.MessageType.TOKEN_RESPONSE:
       goog.global.braintree.setup(goog.object.get(data, 'token'), 'dropin', {