DevTools: Enable devtools extensions support in the worker frontend

R=pfeldman@chromium.org, pfeldman, vsevik
BUG=403087

Review URL: https://codereview.chromium.org/475713002

git-svn-id: svn://svn.chromium.org/blink/trunk@180252 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/devtools/front_end/main/Main.js

@@ -192,7 +192,7 @@ WebInspector.Main.prototype = {
         if (WebInspector.experimentsSettings.documentation.isEnabled())
             configuration.push("documentation");
         if (WebInspector.isWorkerFrontend())
-            configuration = ["main", "sources", "timeline", "profiler", "console", "source_frame"];
+            configuration = ["main", "sources", "timeline", "profiler", "console", "source_frame", "extensions"];
         self.runtime.registerModules(configuration);
     },