Bug 1269349 - make robocop honor --timeout; r=gbrown

Our testsuites normally disable timeouts when --debugger or similar
options are specified.  Robocop doesn't do this, because apparently the
best way to debug Robocop tests is to |mach robocop [TEST-NAMES...]|,
wait for the browser window to show, and then connect a debugger.  This
setup seems suboptimal.

The setup being what it is, though, implies that runrobocop.py has no
knowledge of a debugger being connected, and therefore no idea that the
test really shouldn't time out.  Which then leads to the test going away
at that crucial moment when you are this > < close to figuring out the
bug.  Let's make runrobocop.py understand that --timeout means something
useful for such a context.

testing/mochitest/runrobocop.py

@@ -454,9 +454,12 @@ class RobocopTestRunner(MochitestDesktop):
         log_result = -1
         try:
             self.dm.recordLogcat()
+            timeout = self.options.timeout
+            if not timeout:
+                timeout = self.NO_OUTPUT_TIMEOUT
             result = self.auto.runApp(
                 None, browserEnv, "am", self.localProfile, browserArgs,
-                timeout=self.NO_OUTPUT_TIMEOUT, symbolsPath=self.options.symbolsPath)
+                timeout=timeout, symbolsPath=self.options.symbolsPath)
             self.log.debug("runApp completes with status %d" % result)
             if result != 0:
                 self.log.error("runApp() exited with code %s" % result)