[webapi] Integrate 167 tests for HTML5 Audio

- approved: 111; designed: 56

Impacted tests(approved): new 167, update 0, delete 0
Unit test platform: [IVI] crosswalk-10.38.222, t-e-c 0.107
Unit test result summary: pass 111, fail 24, block 32
We can improve the test files too.

- Here better use `assert_unreached()`
- Remove `<html> <head> <body>`
- Remove `type="text/javascript"` from `<script>`
- Remove end tag ` /` from `<link> <input> <meta> etc.`
- Indent JS code in 2 spaces rather than 4.
- Remove `<meta name="flags" content="" />`