webkit-patch apply-from-bug should work regardless of your CWD

webkit-patch apply-from-bug should work regardless of your CWD
https://bugs.webkit.org/show_bug.cgi?id=77482

Reviewed by Adam Barth.

webkit-patch only ever works with patches made from the root
directory.  We should pass the CWD to svn-apply in the case
where we're running not from the webkit root.  I believe
this used to work in the past and regressed.

* Scripts/webkitpy/common/checkout/checkout.py:
(Checkout.apply_patch):
* Scripts/webkitpy/common/checkout/checkout_unittest.py:
(CheckoutTest.test_apply_patch):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@106396 268f45cc-cd09-0410-ab3c-d52691b4dbfc