jshint: Enable 'es3' option

Syntax new in ES5 not supported in older browsers using ES3.

* Trailing comma's in object and array literals.
* References to properties with protected names.

Disabled for some test files.

Change-Id: I24a0d1677f887097065fab874fea15f3855a4f34
Merge "jshint: Enable 'es3' option"