Revert "Revert "[autotest] TKO parser mark original tests as invalid""

This reverts commit dbd9037df0cbe1232fcb016a2c261f5994ae03a2.

Commit this cl again. Once this cl lands, deploy the db changes together with 

https://chrome-internal-review.googlesource.com/#/c/161494/
https://chrome-internal-review.googlesource.com/#/c/161426/

DEPLOY=apache, migrate, wmatrix db changes should be pushed together (see commit messeage)

Change-Id: I47916708e7b49bbc2064370262e3f9e231f08efe
Reviewed-on: https://chromium-review.googlesource.com/197306
Reviewed-by: Dan Shi <dshi@chromium.org>
Tested-by: Fang Deng <fdeng@chromium.org>
Commit-Queue: Fang Deng <fdeng@chromium.org>
diff --git a/frontend/tko/models.py b/frontend/tko/models.py
index a9c6bf0..286279b 100644
--- a/frontend/tko/models.py
+++ b/frontend/tko/models.py
@@ -210,6 +210,10 @@
     machine = dbmodels.ForeignKey(Machine, db_column='machine_idx')
     finished_time = dbmodels.DateTimeField(null=True, blank=True)
     started_time = dbmodels.DateTimeField(null=True, blank=True)
+    invalid = dbmodels.BooleanField(default=False)
+    invalidates_test = dbmodels.ForeignKey(
+            'self', null=True, db_column='invalidates_test_idx',
+            related_name='invalidates_test_set')
 
     objects = model_logic.ExtendedManager()