Add linux-layout-tests-fragment-paint try bot.

This trybot runs webkit layout tests with NGFragmentPaint runtime flag
set.

[email protected], [email protected]

Bug: 1015029
Change-Id: I718e79aeaf4dc547caddd4889fb0fc3f0b8b44d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1875513
Commit-Queue: Arthur Wang <[email protected]>
Reviewed-by: Aaron Gable <[email protected]>
Reviewed-by: John Budorick <[email protected]>
Cr-Commit-Position: refs/heads/master@{#713071}
diff --git a/testing/buildbot/test_suite_exceptions.pyl b/testing/buildbot/test_suite_exceptions.pyl
index 30833a6..80e3e90 100644
--- a/testing/buildbot/test_suite_exceptions.pyl
+++ b/testing/buildbot/test_suite_exceptions.pyl
@@ -2112,6 +2112,11 @@
           '--additional-driver-flag=--enable-blink-features=LayoutNGFragmentItem',
         ],
       },
+      'linux-layout-tests-fragment-paint': {
+        'args': [
+          '--additional-driver-flag=--enable-blink-features=LayoutNGFragmentPaint',
+        ],
+      },
       # client.v8.fyi
       'V8 Blink Linux Debug': {
         'args': [