Fix typo from commit d3611f.

TBR=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1242493003 .
diff --git a/testing/tools/run_corpus_tests.py b/testing/tools/run_corpus_tests.py
index ba014d4..28616fb 100755
--- a/testing/tools/run_corpus_tests.py
+++ b/testing/tools/run_corpus_tests.py
@@ -73,7 +73,7 @@
                failures.append(input_path)
 
   if surprises:
-    surprise.sort()
+    surprises.sort()
     print '\n\nUnexpected Successes:'
     for surprise in surprises:
       print surprise;