[test] Fix predictable mode with output processors

Bug: v8:6917
Change-Id: I7bc5d09ff19a9cf7cb4bee68ca6cf34f5cfa8b19
Reviewed-on: https://chromium-review.googlesource.com/850874
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50365}

tools/testrunner/objects/predictable.py

@@ -22,7 +22,7 @@ def get_outproc(test):
 
 
 class OutProc(outproc_base.BaseOutProc):
-  """Output processor wrapper for predictable mode. It has custom
+  """Output processor wrapper for predictable mode. It has custom process and
   has_unexpected_output implementation, but for all other methods it simply
   calls wrapped output processor.
   """
@@ -31,7 +31,7 @@ class OutProc(outproc_base.BaseOutProc):
     self._outproc = _outproc
 
   def process(self, output):
-    return self._outproc.process(output)
+    return outproc_base.Result(self.has_unexpected_output(output), output)
 
   def has_unexpected_output(self, output):
     return output.exit_code != 0