LeakExpectations: Add more isolated world test

TBR=haraken
NOTRY=true
BUG=364377

Review URL: https://codereview.chromium.org/342883002

git-svn-id: svn://svn.chromium.org/blink/trunk@176470 bbb929c8-8fbe-4397-9dbb-9b2b20218538