[misc][XWALK-1847] Replace picture URL in Resource Timing

- Old picture URL is invalid now, so need to relpace.

Impacted TCs num(approved): New 0, Update 1, Delete 0
Unit test Platform: Tizen M0
Tizen test result summary: Pass 1, Fail 0, Blocked 0
This makes the test depend on test.csswg.org!

Anyway, this image is there. Merge this pull request as-is.