[xwalk-2832] create a case to test to call bluetooth.getDefaultAdapter()...

Impacted tests: new 1, update 0, delete 0
Unit test platform: [IVI] crosswalk-10.38.222, t-e-c 0.107
Unit test result summary: pass 0, fail 1, block 0
Is this a sub-app name? Seems it has the same name as test suite.