[webapi][XWALK-2147] Add default color reference on page
[webapi][XWALK-522] Optimize the test cases for promises

Impacted tests(approved): new 1, update 3, delete 0
Unit test platform: [Android]
Unit test result summary: pass 4, fail 0, block 0
[usecase-webapi] Disable forward button and show history state
[wrt][XWALK-1591]Fix XWALK-1591

[Detailed commit message (if have)]
Impacted TCs num(approved): New 0, update 3, deleted 0
Unit test platform: [tizen]
Unit test result summary: Pass 3, Fail 0, Blocked 0
[wrt]update wrt test suite name

Unit test platform: [tizen]
Unit test result summary: Auto suite pack to pure, manu suite pack to wgt
Fix for tct-extra-html5-tests/base64.html

[Problem] The following test cases from tct-extra-html5-tests/base64 fail
    - base64_atob_ab_cd
    - base64_atob_abcd_space
    - base64_atob_space_abcd
[Cause] Those test cases fails since  Chromium implements the newest
        standard of base64 feature but the test has not been updated yet.

[Solution] Apply latest changes of base64.html from
           http://w3c-test.org/html/webappapis/atob/base64.html

BUG=XWALK-2227
[usecase-webapi] Improve Page Visibility usecase

- add description of locking screen/unlocking screen

Impacted TCs num(approved): New 0, Update 1, Delete 0
Unit test Platform: [Andriod]
Test result summary: Pass 1, Fail 0, Blocked 0
[usecase-webapi] Improve CSP usecase

- Add notice in csp-none page

Impacted TCs num(approved): New 0, Update 1, Delete 0
Unit test Platform: [Andriod]
Test result summary: Pass 1, Fail 0, Blocked 0
Merge pull request #581 from JianfengXu/xujf/csp/update

[usecase-webapi] Improve CSP usecase
Merge pull request #551 from zhuyongyong/yongzhu/sessionHistory/begining

[usecase-webapi] Disable forward button and show history state
Merge pull request #530 from zhuyongyong/yongzhu/promise-optimize

[webapi][XWALK-522] Optimize the test cases for promises
Merge pull request #580 from zhangjingx/zhangjingx/misc/pagevisibility

[usecase-webapi] Improve Page Visibility usecase
[usecase-webapi] Improve Navigation Timing usecase

- Group the timing checkpoints in a div, add a a reload button.

Impacted TCs num(approved): New 0, Update 1, Delete 0
Unit test Platform: Tizen M0
Tizen test result summary: Pass 1, Fail 0, Blocked 0
[misc-cordove] Improve cordova usecase description
Merge pull request #623 from xinliux/xinliux/usecase/navigationtiming-improve

[usecase-webapi] Improve Navigation Timing usecase
[wrt]Update pack.sh to wrt-i18nmanu-tizen-tests

Unit test platform: [tizen]
Unit test result summary: Pack to wgt and pass 1 , Fail 0, Blocked  0
[usecase-wrt] Update usecase framework for wrt-usecase-android-tests
[wrt] Update suite name in xml for wrt-rtcoremanu-android-tests
Merge pull request #630 from kangxu/kangxu/wrt/wrt-rtcoremanu-android-tests/updateSuiteName

[wrt][XWALK-2241] Update suite name in xml for wrt-rtcoremanu-android-tests
Merge pull request #624 from wanghongjuan/wanghongjuan/misc/cordova-improve

[misc-cordove] Improve cordova usecase description