[Chromium] Unreviewed gardening.
Remove two now-passing tests.

* platform/chromium/TestExpectations:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@143375 268f45cc-cd09-0410-ab3c-d52691b4dbfc
Add a test result missed in r143074.

* platform/mac-wk2/tiled-drawing/null-parent-back-crash-expected.txt: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@143376 268f45cc-cd09-0410-ab3c-d52691b4dbfc