[webapi] Remove 3 tests for CSS3 Background due to spec update

- box-decoration-break has been removed from new spec
http://www.w3.org/TR/2014/WD-css3-background-20140204/

Impacted tests(approved): new 0, update 0, delete 3
Unit test platform: [Android][IVI]
Unit test result summary: pass 538, fail 0, block 0
[webapi][XWALK-2533] Fix bug for mediarenderer

- Fix bug for mediarenderer

Impacted tests(approved): new 0, update 1, delete 0
Unit test platform: [Tizen IVI]
Unit test result summary: pass 1, fail 0, block 0
[webapi]Increase timeout for align-items-005.htm to overcome this case block issue.

Impacted tests(approved):new 0,update 1,delete 0
Unit test platform:[Android]
Unit test result summary:pass 0,fail 1,block 0
[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 #989 from kangxu/kangxu/webapi/tct-backgrounds-css3-tests/removeCases

[webapi] Remove 3 tests for CSS3 Background due to spec update
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
[usecase-webapi] Remove SpeechSynthesis from tests.android.xml & tests.tizen.xml

 - The feature is not resolved.
Merge pull request #1013 from yunxiaoxie/yunxiaoxie/speechsynthesisfixconfig

[usecase-webapi] Remove SpeechSynthesis from tests.android.xml & tests.t...
Merge pull request #1003 from chenxix/chenxi/misc-uiautomation/modify-flexible

 [webapi] Increase timeout attribute for align-items-005.htm to overcome this case block issue.
Merge pull request #996 from yunxliu/yunxliu/webapi/mediarenderer

[webapi][XWALK-2533] Fix bug for mediarenderer
[usecase] Update install command in inst.wgt/xpk.py
Merge pull request #1014 from Honry/Honry/usecase/update-install-command

[usecase] Update install command in inst.wgt/xpk.py
[webapi] Improve 3 cases for Selectors API Level2

Impacted tests(approved): new 0, delete 0, update 3
Unit test platform: [Android][IVI]
Unit test result summary: pass 3, fail 0, block 0
Merge pull request #998 from kangxu/kangxu/webapi/tct-selectorslevel2-w3c-tests/updateCases

[webapi] Improve 3 cases for Selectors API Level 2
[wrt][WEBQA-154] Add a file .gitkeep

- Build apk successfully, no error

Impacted TCs num(approved): New 0, Update 1, Delete 0
Unit test Platform: Android
Android test result summary: Pass 1, Fail 0, Block 0
Merge pull request #1016 from wanghongjuan/wanghongjuan/wrt/WEBQA-154

[wrt][WEBQA-154] Add a file .gitkeep