Do not block all task manager tree view mouse release events.
Do not block all task manager tree view mouse release events.

BUG=16974
TEST=you can resize rows of the task manager

Review URL: http://codereview.chromium.org/155670

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@21006 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser