Changeset 37723 for trunk/tests/phpunit/tests/dependencies/backbonejs.php

External Libraries: Update Backbone to version 1.3.3.

Changelog: ​https://cdn.rawgit.com/jashkenas/backbone/1.3.3/index.html#changelog
Diff: ​https://github.com/jashkenas/backbone/compare/1.2.3...1.3.3

Includes a unit test to ensure that the minified version doesn't include sourceMappingURL.

Props adamsilverstein.
Fixes #37099.