Web Inspector: fix code-mirror experiment to work in debug mode
https://bugs.webkit.org/show_bug.cgi?id=111064

Patch by Andrey Lushnikov <lushnikov@chromium.org> on 2013-03-01
Reviewed by Pavel Feldman.

No new tests: no change in behaviour.

Improve importScript function to try load a script from the root
directory iff its loading from the given path failed.

* inspector/front-end/utilities.js:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@144428 268f45cc-cd09-0410-ab3c-d52691b4dbfc