Temporary GC fuzzer.

Temporary implementation of GC fuzzer based on the deopt fuzzer.
It will be merged with the deopt fuzzer to create more general numfuzzer.

Webkit test suite updated to ignore trace_incremental_marking flag output.

Bug: v8:6917
Change-Id: I053ae32f3cd3f74ba8b71fc5bdfc7264f54dca11
Reviewed-on: https://chromium-review.googlesource.com/758437
Commit-Queue: Michał Majewski <majeski@google.com>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49296}

test/webkit/testcfg.py

@@ -103,10 +103,11 @@ class WebkitTestSuite(testsuite.TestSuite):
 
   # TODO(machenbach): Share with test/message/testcfg.py
   def _IgnoreLine(self, string):
-    """Ignore empty lines, valgrind output and Android output."""
+    """Ignore empty lines, valgrind output, Android output and trace
+    incremental marking output."""
     if not string: return True
     return (string.startswith("==") or string.startswith("**") or
-            string.startswith("ANDROID") or
+            string.startswith("ANDROID") or "[IncrementalMarking]" in string or
             # FIXME(machenbach): The test driver shouldn't try to use slow
             # asserts if they weren't compiled. This fails in optdebug=2.
             string == "Warning: unknown flag --enable-slow-asserts." or

tools/run-gc-fuzzer.py

+#!/usr/bin/env python
+#
+# Copyright 2017 the V8 project authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+
+import sys
+
+from testrunner import gc_fuzzer
+
+
+if __name__ == "__main__":
+  sys.exit(gc_fuzzer.GCFuzzer().execute())