[wrt]XWALK-1731 Update test.xml to approve the backend tcs

[Detailed commit message (if have)]
Impacted TCs num(approved): New 0, update 3 , deleted 0
Unit test platform: [tizen]
Test Result: Pass 3, Fail 0
Merge pull request #1011 from linshen/shenlin/update-1731-to-approved

[wrt]XWALK-1731 Update test.xml to approve the backend tcs
[webapi] Remove support.js in tct-xmlhttprequest-w3c-tests

Impacted tests(approved): new 0, update 8, delete 0
Unit test platform: [Android]
Unit test result summary: pass 214, fail 19, block 1

Comment: Fail to get correct value of "header.toLowerCase()"
when running "w3c/xmlhttprequest" on Android OS
Merge pull request #1000 from kangxu/kangxu/webapi/tct-xmlhttprequest-w3c-tests/updateCases

[webapi] Remove support.js in tct-xmlhttprequest-w3c-tests
[webapi] Update cases due to spec update for Battery Status API

- New spec:https://dvcs.w3.org/hg/dap/raw-file/default/battery/Overview.html

Impacted tests(approved): new 9, update 0, delete 24
Unit test platform: [Android][IVI]
Unit test summary: pass 9, fail 0, block 0
Merge pull request #1009 from kangxu/kangxu/webapi/tct-batterystatus-w3c-tests/updateCases

[webapi] Update cases due to spec update for Battery Status API