[usecase] Update usecase for SpeechSynthesis

Impacted tests(approved): new 0, update 1, delete 0
Unit test platform: [IVI]
Unit test result summary: pass 1, fail 0, block 0
[webapi] Fix 2 tests for Audio & Video

Impacted tests(approved): new 0, update 2, delete 0
Unit test platform: [IVI]
Unit test result summary: pass 2, fail 0, block 0
[wrt][webqa-164] Update test script entry
Merge pull request #1415 from haoxli/wrt/webqa-164

[wrt][webqa-164] Update test script entry
Merge pull request #1411 from kangxu/kangxu/usecase/SpeechSynthesis/update

[usecase] Update usecase for SpeechSynthesis
Merge pull request #1414 from yunxiaoxie/canPlayType-null2

[webapi] Fix 2 tests for Audio & Video