Clean up node_modules

Reviewed By: bestander

Differential Revision: D3168034

fb-gh-sync-id: bf4c5d44bb10989ac838f3d150c0931fadadfa7b
fbshipit-source-id: bf4c5d44bb10989ac838f3d150c0931fadadfa7b

package.json

@@ -142,6 +142,7 @@
     "bser": "^1.0.2",
     "chalk": "^1.1.1",
     "connect": "^2.8.3",
+    "core-js": "^2.2.2",
     "debug": "^2.2.0",
     "event-target-shim": "^1.0.5",
     "fbjs": "^0.7.2",