Merge pull request #7960 from yurenju/travis

Bug 837581 - Added travis.sh for travis integration(cherry picked from commit 0f31fd5abf3f67c1ba4d826d50ad3fddb95bf801)
Merge pull request #8352 from etiennesegonzac/bug-835637-stk-race-issue

Bug 835637 - STK test case(cherry picked from commit 3f69c326ec7d7318829a39afe9ca8c0a45ef0996)
Merge pull request #8252 from davidflanagan/bug837909

Bug 837909 - start zooming in on preview image, then transition to fullsize r=daleharvey(cherry picked from commit 945074923daa296c135de87f4215aedd4d88f4b8)
Merge pull request #8251 from KevinGrandon/bug_818765_task_switcher

Bug 818765 - Task switcher performance updates(cherry picked from commit e2d0d82eb3db1509c2d1cb173e0941253c23cc2e)
Merge pull request #8356 from etiennesegonzac/bug-833708-landing

Bug 833708: Correctly handle update errors that happen in-stack while se...(cherry picked from commit ec6d010f907a69059853b20c36a5117cf890e8d5)