[webapi][xwalk-2123] Update exception name in tests.xml

- Tests have been updated in PR#861, update test purpose in tests.xml
- Pass on Crosswalk 9.38.202.0, but fail on Crosswalk 9.38.199.0

Impacted tests(approved): new 0, update 5, delete 0
Unit test platform: [Tizen IVI]
Unit test result summary: pass 5, fail 0, block 0