[test] Fix timeout-scalefactor for numfuzzer

TBR=majeski@google.com
NOTRY=true

Bug: v8:6917
Change-Id: I088dc4492df6c1dda1f86fbd6d7153a46a4117e0
Reviewed-on: https://chromium-review.googlesource.com/895600Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51000}

tools/testrunner/num_fuzzer.py

@@ -122,6 +122,7 @@ class NumFuzzer(base_runner.BaseTestRunner):
       # TODO(machenbach): This should be moved to a more generic config.
       # Fuzzers have too much timeout in debug mode.
       factor = max(int(factor * 0.25), 1)
+    return factor
 
 
   def _do_execute(self, suites, args, options):