Add a test to verify that the breakpad symbol-generating script actually exists.

Add a test to verify that the breakpad symbol-generating script actually exists.

We moved the file as part of the work to rename //components/breakpad to
//components/crash, but failed to update the path in webkitpy.

It seems like a generally good idea to verify that the script does exist,
as we clearly didn't have other test coverage for this and were just getting
strange failures in run-webkit-tests.

R=rsesek@chromium.org
BUG=406410, 408644
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=181128

[Dirk Pranke, 2014-08-29 23:55:41]

dpranke@chromium.org changed reviewers:
+ rtoy@chromium.org

[Robert Sesek, 2014-08-30 01:06:23]

lgtm

[Dirk Pranke, 2014-08-30 01:14:58]

The CQ bit was checked by dpranke@chromium.org

[commit-bot: I haz the power, 2014-08-30 01:15:31]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/dpranke@chromium.org/518363002/1

[commit-bot: I haz the power, 2014-08-30 02:21:57]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  linux_blink_dbg on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/linux_blink_dbg/builds/2...)

[commit-bot: I haz the power, 2014-08-30 03:26:22]

Committed patchset #1 (id:1) as 181128