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
    []

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

javatests/google/registry/ui/js/testing.js

@@ -131,7 +131,7 @@ registry.testing.assertReqMockRsp =
   // XXX: XHR header checking should probably be added. Was inconsistent
   //      between admin and registrar consoles.
   registry.testing.assertObjectEqualsPretty(
-      expectReqJson, goog.json.parse(xhr.getLastContent()));
+      expectReqJson, JSON.parse(xhr.getLastContent()));
   xhr.simulateResponse(200, goog.json.serialize(mockRspJson));
 };