Added linux-blink-heap-concurrent-marking-tsan-rel builder.

Blink bot for concurrent marking.

Bug: 945858
Change-Id: Ib88047bc251bcd70c977f6db82e3d076f085f54c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1535050
Commit-Queue: Karen Qian <[email protected]>
Reviewed-by: John Budorick <[email protected]>
Cr-Commit-Position: refs/heads/master@{#646513}
diff --git a/testing/buildbot/test_suite_exceptions.pyl b/testing/buildbot/test_suite_exceptions.pyl
index 0aaf3d1..8c8ddaa 100644
--- a/testing/buildbot/test_suite_exceptions.pyl
+++ b/testing/buildbot/test_suite_exceptions.pyl
@@ -1548,6 +1548,12 @@
           '--debug',
         ],
       },
+      'linux-blink-heap-concurrent-marking-tsan-rel': {
+        'args': [
+          '--release',
+          '--additional-driver-flag=--enable-blink-features=HeapConcurrentMarking',
+        ],
+      },
       'linux-blink-heap-unified-gc': {
         'args': [
           '--debug',