[autotest] Finish --stably_only impl in suite_enumerator.py

Make --stable_only actually print only stable tests in the given suite.
BUG=chromium-os:26942
TEST=add EXPERIMENTAL=True to a control file in the bvt, then run ./site_utils/suite_enumerator.py -s -a . bvt 2>/dev/null  and the see that the control file you modified is not listed.
STATUS=Fixed

Change-Id: Ibfe1100f3de748a6ea641237ced3a50e1147cf6d
Reviewed-on: https://gerrit.chromium.org/gerrit/17061
Tested-by: Chris Masone <cmasone@chromium.org>
Reviewed-by: Zdenek Behan <zbehan@chromium.org>
Reviewed-by: Chris Sosa <sosa@chromium.org>
Commit-Ready: Chris Masone <cmasone@chromium.org>
diff --git a/site_utils/suite_enumerator.py b/site_utils/suite_enumerator.py
index df35918..f29c0fe 100755
--- a/site_utils/suite_enumerator.py
+++ b/site_utils/suite_enumerator.py
@@ -46,8 +46,11 @@
 
     fs_getter = dynamic_suite.Suite.create_fs_getter(options.autotest_dir)
     suite = dynamic_suite.Suite.create_from_name(args[0], '', fs_getter)
-    for test in suite.tests:
+    for test in suite.stable_tests():
         print test.path
+    if options.add_experimental:
+        for test in suite.unstable_tests():
+            print test.path
 
 
 if __name__ == "__main__":