[Alarm] Fix failures raised from test suite.

I've downloaded the test suite from http://otcqa.sh.intel.com/qa-auto/live/Web_TCT_Xwalk/ and run them manually.
All the alarm related failures in the test suite have been fixed.

BUG=XWALK-2163
Thanks for reviewing, probably the `toString()` has better readability, however we need to get used to Javascript coding style, right:).
The http://jsperf.com/ would be optional tool when we need to tune our JS code performance.