[chromium] Update test expectations
https://bugs.webkit.org/show_bug.cgi?id=107328

Not reviewed. Mark this test as MISSING:
http/tests/cache/cancel-multiple-post-xhrs.html

* platform/chromium/TestExpectations:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@140210 268f45cc-cd09-0410-ab3c-d52691b4dbfc