[test] Allow timeouts for benchmarks with gc fuzzer

TBR=sergiyb@chromium.org

Bug: v8:6917
Change-Id: I592f745385fe0aedf2d9fb6f88e51b85663c6865
Reviewed-on: https://chromium-review.googlesource.com/891821
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50947}

test/benchmarks/testcfg.py

@@ -104,6 +104,9 @@ class TestSuite(testsuite.TestSuite):
   def _test_class(self):
     return TestCase
 
+  def _suppressed_test_class(self):
+    return SuppressedTimeoutTestCase
+
 
 class TestCase(testcase.TestCase):
   def _get_files_params(self, ctx):
@@ -133,5 +136,12 @@ class TestCase(testcase.TestCase):
     return os.path.join(self.suite.testroot, self.path + self._get_suffix())
 
 
+class SuppressedTimeoutTestCase(TestCase):
+  """The same as a standard test case allowing timeouts."""
+  def _prepare_outcomes(self, *args, **kwargs):
+    super(SuppressedTimeoutTestCase, self)._prepare_outcomes(*args, **kwargs)
+    self.expected_outcomes = self.expected_outcomes + [statusfile.TIMEOUT]
+
+
 def GetSuite(name, root):
   return TestSuite(name, root)