webtry: Reuse util's ReportError function.

both webtry's reportError and util's ReportError functions are almost
exactly the same. So lets move to the shared one.

BUG=None
R=humper@google.com

Review URL: https://codereview.chromium.org/763163002
Alertserver fixes

BUG=skia:3171

Review URL: https://codereview.chromium.org/775643002
Fix bugs in setup script

BUG=skia:
TBR=borenet

Review URL: https://codereview.chromium.org/769273003