[webapi][xwalk-3192] Sync w3c currentSrc tests for HTML Audio&Video

- Update currentSrc tests of Audio and Video to w3c latest

Impacted tests(approved): new 0, update 6, delete 0
Unit test platform: [IVI]
Unit test result summary: pass 6, fail 0, block 0
Merge pull request #1510 from haoxli/webapi/xwalk-3192

[webapi][xwalk-3192] Sync w3c currentSrc tests for HTML Audio&Video