[webapi] Fixed XWALK-1735 by updating notification TC to auto

Impacted Suites: tct-notification-w3c-tests
Impacted TCs num: New 0, Update 1, Delete 0
Unit test platform: Tizen(IVI), 
Tizen test result summary: Pass 0, Fail 1, Blocked 0

Fail reason: notification does not support  on IVI platform
s/assert_true(false/assert_unreached/