[test] Always pre-sort test cases marked as slow.

On bots we don't sort due to not being able to store the duration DB. But we should still run the tests marked as slow first.

BUG=v8:5861

Change-Id: Ifa812b3eef15f48e3d3c752c14c3f546b5dd87d1
Reviewed-on: https://chromium-review.googlesource.com/439284Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43057}

tools/testrunner/local/execution.py

@@ -197,12 +197,17 @@ class Runner(object):
     self.perf_failures = False
     self.printed_allocations = False
     self.tests = [ t for s in suites for t in s.tests ]
+
+    # Always pre-sort by status file, slowest tests first.
+    slow_key = lambda t: statusfile.IsSlow(t.outcomes)
+    self.tests.sort(key=slow_key, reverse=True)
+
+    # Sort by stored duration of not opted out.
     if not context.no_sorting:
       for t in self.tests:
         t.duration = self.perfdata.FetchPerfData(t) or 1.0
-      slow_key = lambda t: statusfile.IsSlow(t.outcomes)
-      self.tests.sort(key=slow_key, reverse=True)
       self.tests.sort(key=lambda t: t.duration, reverse=True)
+
     self._CommonInit(suites, progress_indicator, context)
 
   def _CommonInit(self, suites, progress_indicator, context):