Revert "Bug 845487 - Dialer responds to cross-origin messages without verifying the source (exploitable)."

This reverts commit 7e0e1b8925214718c400dcdecbe680c8c64b68d8.

Unfortunately the commit breaks the linter and should be backed out according to our process.

make lint
Skipping 45 file(s).
----- FILE : /home/travis/build/mozilla-b2g/gaia/apps/communications/contacts/oauth2/js/oauth20.js -----
Line 84, E:0131: Single-quoted string preferred over double-quoted string.
Line 107, E:0131: Single-quoted string preferred over double-quoted string.

Found 2 errors, including 0 new errors, in 1 files (604 files OK).