Add 'sw-e10s' to run_info_extras

Differential Revision: https://phabricator.services.mozilla.com/D9585

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1501426
gecko-commit: dce16565d2a8c37e885b9e105ffcb78a0e6458db
gecko-integration-branch: autoland
gecko-reviewers: jmaher
diff --git a/tools/wptrunner/wptrunner/browsers/fennec.py b/tools/wptrunner/wptrunner/browsers/fennec.py
index 15f6c00..c783006 100644
--- a/tools/wptrunner/wptrunner/browsers/fennec.py
+++ b/tools/wptrunner/wptrunner/browsers/fennec.py
@@ -111,7 +111,8 @@
 
 def run_info_extras(**kwargs):
     return {"e10s": False,
-            "headless": False}
+            "headless": False,
+            "sw-e10s": False}
 
 
 def env_options():