Fix build errors.

packages/faq-extension/package.json

@@ -34,9 +34,7 @@
     "@jupyterlab/application": "^0.16.2",
     "@jupyterlab/apputils": "^0.16.3",
     "@jupyterlab/rendermime": "^0.16.2",
-    "@phosphor/coreutils": "^1.3.0",
-    "@phosphor/messaging": "^1.2.2",
-    "@phosphor/widgets": "^1.5.0"
+    "@phosphor/coreutils": "^1.3.0"
   },
   "devDependencies": {
     "@types/node": "~8.0.47",

packages/help-extension/package.json

@@ -35,7 +35,6 @@
     "@jupyterlab/coreutils": "^1.1.2",
     "@jupyterlab/mainmenu": "^0.5.2",
     "@jupyterlab/services": "^2.0.2",
-    "@phosphor/messaging": "^1.2.2",
     "@phosphor/widgets": "^1.5.0",
     "react": "~16.2.0"
   },

packages/help-extension/src/index.tsx

@@ -21,10 +21,6 @@ import {
   KernelMessage
 } from '@jupyterlab/services';
 
-import {
-  Message
-} from '@phosphor/messaging';
-
 import {
   Menu
 } from '@phosphor/widgets';

packages/notebook-extension/src/index.ts

@@ -56,7 +56,7 @@ import {
 } from '@phosphor/messaging';
 
 import {
-  Menu, Widget
+  Menu
 } from '@phosphor/widgets';