(cherry picked from commit 6c29dd24)

(cherry picked from commit 0a3a424e)

(cherry picked from commits 36457cb6..f860e0bd)

(cherry picked from commit 9cf812d7)

Revert grunt, grunt-contrib-jshint, and grunt-contrib-uglify versions used in build until we can adapt Gruntfile to support grunt 0.4.0rc5 changes

Cherry picked from e348b406 .

Adjusts unit test regarding exception in injected scripts so that it accounts for the exception being thrown in an event loop for remote scripts

Opera 12.0 still implements an older version of the DOM so cloneNode cannot be called without an argument

Tweaks the logic in the 304-related unit tests so that they pass for versions of Opera that support manual 304 handling as well as for those that don't

Fixes comments per @rwldrn. Makes sure failing requests from local protocol yields status 404, not 0.

Check removed in the initial 2.0 refactor but Chrome still needs it. No effective way to unit test; see the test case in #13143.