[BUGFIX beta] Fix feature flagged tests.

Updates `ember-dev` to resolve an issue introduced with
https://github.com/emberjs/ember.js/pull/4045 that caused the test
harness to always ignore feature flagged tests.
Merge pull request #4057 from rjackson/fix_feature_flagged_tests

[BUGFIX beta] Fix feature flagged tests.
[BUGFIX beta] replaceURL checks of URL has actually changed

Fixes #4054