Limit number of opened tabs in brower

Limit number of opened tabs in brower

[Issue]        https://bugs.tizen.org/jira/browse/TT-174
[Problem]      When more than 30 tabs are opened the browser crashes.
[Solution]     Limit the number of simultaneously opened tabs to 10.
               If user wants to add another tab, popup is shown.
               WebCore Part must check, if sending out=NULL in __newWindowRequest doesn't create
               another bug.
[Verification] Please open 10 tabs and try to add another one, with either + in tab manager
               or "Open link in new tab" in popup.

Change-Id: I342fe4dda10e6ae11e2199893ce3a8412c01227e