DevTools: extract the dom_extension module.

third_party/WebKit/Source/devtools/front_end/unit_test_runner.json

Index: third_party/WebKit/Source/devtools/front_end/unit_test_runner.json
diff --git a/third_party/WebKit/Source/devtools/front_end/unit_test_runner.json b/third_party/WebKit/Source/devtools/front_end/unit_test_runner.json
index 50cd288a4006c19341ada442d45686ec258a44a8..f10b33b365724d03654b01eafe2a8abaf20741e8 100644
--- a/third_party/WebKit/Source/devtools/front_end/unit_test_runner.json
+++ b/third_party/WebKit/Source/devtools/front_end/unit_test_runner.json
@@ -1,6 +1,7 @@
 {
     "modules" : [
         { "name": "platform", "type": "autostart" },
+        { "name": "dom_extension", "type": "autostart" },
         { "name": "ui", "type": "autostart" },
         { "name": "host", "type": "autostart" },
         { "name": "common", "type": "autostart" },
@@ -15,4 +16,4 @@
         { "name": "quick_open" }
     ],
     "has_html": true
-}
+}