Enable tests of chrome.tab.captureVisibleTab() on mac, and all tab tests on linux.
Enable tests of chrome.tab.captureVisibleTab() on mac, and all tab tests on linux.

BUG=39746,37387

Review URL: http://codereview.chromium.org/1540010

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@43393 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