Change ref test in tct-backgrounds-css3-tests

[webapi]Add 14 reference files for 24 tests

Impacted tests(approved):new 0,update 24,delete 0
Unit test platform:[Android]
Unit test result summary:pass 2,fail 22,block 0
Merge pull request #846 from chenxix/chenxi/misc-uiautomation/css-background

Change ref test in tct-backgrounds-css3-tests