[Chromium] Rebaseline svg/filters/sourceAlpha.svg on mac

[Chromium] Rebaseline svg/filters/sourceAlpha.svg on mac
https://bugs.webkit.org/show_bug.cgi?id=84069

Unreviewed Chromium test expectations update.

Finally closing out an expectations update from 2009.

* platform/chromium-mac-leopard/svg/filters/sourceAlpha-expected.png: Added.
* platform/chromium-mac-snowleopard/svg/filters/sourceAlpha-expected.png:
* platform/chromium-mac/svg/filters/sourceAlpha-expected.png: Added.
* platform/chromium/test_expectations.txt:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@114294 268f45cc-cd09-0410-ab3c-d52691b4dbfc