Clean up dependencies

packages/cells/package.json

@@ -40,12 +40,10 @@
     "@phosphor/messaging": "^1.2.1",
     "@phosphor/signaling": "^1.2.1",
     "@phosphor/widgets": "^1.3.0",
-    "react": "^15.6.2",
-    "react-dom": "^15.6.2"
+    "react": "^15.6.2"
   },
   "devDependencies": {
     "@types/react": "^15.6.2",
-    "@types/react-dom": "^15.5.6",
     "rimraf": "^2.5.2",
     "typescript": "~2.4.1"
   }

packages/launcher/package.json

@@ -34,7 +34,8 @@
     "@phosphor/coreutils": "^1.2.0",
     "@phosphor/disposable": "^1.1.1",
     "@phosphor/messaging": "^1.2.1",
-    "@phosphor/widgets": "^1.3.0"
+    "@phosphor/widgets": "^1.3.0",
+    "react": "^15.6.2"
   },
   "devDependencies": {
     "@types/react": "^15.6.2",