1422006 - Support running gtest with |mach test|

Status: NEW

(Testing :: GTest, enhancement)

Description

[Andrew Halberstadt [:ahal]]

+++ This bug was initially created as a clone of Bug #1422005 +++

Running |mach test gtest| results in:
UNKNOWN TEST: gtest
I was unable to find tests from the given argument(s).

You should specify a test directory, filename, test suite name, or
abbreviation. If no arguments are given, there must be local file
changes and corresponding IMPACTED_TESTS annotations in moz.build
files relevant to those files.

It's possible my little brain doesn't know about the type of test you are
trying to execute. If you suspect this, please request support by filing
a bug at
https://bugzilla.mozilla.org/enter_bug.cgi?product=Testing&component=General.

We should add support for this suite.