Fix the issue Browser freeze when dragging the page and rotate the phone at the same times

When drag event is cancelled, the tab removing isn't needed. Or if it is the last one, browser will be closed and windows manager may be ANR.

Change-Id: Ia786d98727cecbe303cf9d153a471fd4a165b797
Author: Weiwei Ji <weiweix.ji@intel.com>
Signed-off-by: Xiaokang Qin <xiaokang.qin@intel.com>
Signed-off-by: Bruce Beare <bruce.j.beare@intel.com>
Signed-off-by: Jack Ren <jack.ren@intel.com>
Author-tracking-BZ: 30621