[webapi] Integrate 21 tests for HTML5 Canvas

- approved: 15
- Another 6 cases have been removed.

Impacted tests(approved): new 15, update 0, delete 0
Unit test platform: [IVI] crosswalk-10.38.222, t-e-c 0.107
Unit test result summary: pass 14, fail 1, block 0
Merge pull request #1201 from xinliux/canvas-integrate

[webapi] Integrate 21 tests for HTML5 Canvas