[webapi][XWALK-522] TCs for promises

- Add new 3 TCs for webapi-promises-nonw3c-tests

Impacted tests(approved): new 3, update 0, delete 0
Unit test platform: [Android]
Unit test result summary: pass 3, fail 0, block 0
You don't need the indent here.

Another, what's the relationship with #318 ?