[wrt][xwalk-3043] Fix wgt path not found

Impacted tests(approved): new 0, update 1, delete 0
Unit test platform: [Tizen]
Unit test result summary: pass 1, fail 0, block 0
Merge pull request #1330 from haoxli/wrt/xwalk-3043

[wrt][xwalk-3043] Fix wgt path not found