Rebaseline compositing/images/direct-image-dynamic-clip-path.html

Delete mac result, rebaseline to grab any new mac result, which should
match the windows result and be optimized out if things are working as
expected per issue 405803 and issue 409435.

BUG=405803
TBR=dstockwell@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/697843005

git-svn-id: svn://svn.chromium.org/blink/trunk@185102 bbb929c8-8fbe-4397-9dbb-9b2b20218538