[Mac] In -[TabView mouseUp:] handle rapid closure before sending the target/action.
[Mac] In -[TabView mouseUp:] handle rapid closure before sending the target/action.

BUG=88916
TEST=Open a lot of tabs to get them small without a close button. Close the active tab and, while keeping the mouse in the tab strip, move to another tab and click on it. It does not close.
TEST=Open a few tabs and close one of the ones in the middle. Without moving the moues, click again to close the next, and so on (i.e. rapid tab closure).

Review URL: http://codereview.chromium.org/7472010

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@93389 0039d316-1c4b-4281-b951-d872f2087c98

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