[misc-uiautomation] Add reference file for html5-extra

Impacted tests: new 0, update 3, delete 0
Unit test platform: [Chromium]
Unit test result summary: pass 3, fail 0, block 0
For one thing, I don't find any statement in the spec that the `<mark>` behaviors like a yellow background for highlighting text; for another, better use `background-color`.

Moreover, current being reference matches with test file on Chrome 35 and Opera 12.16; but failed on IE 10 and Firefox 30 because they have different text font. Please double check it.