Remove leftover deps (#939)

Author: ovidiuch

packages/react-cosmos-fixture/package.json

@@ -6,7 +6,6 @@
   "license": "MIT",
   "main": "index.js",
   "dependencies": {
-    "@babel/runtime-corejs2": "^7.3.1",
     "lodash": "^4.17.11",
     "memoize-one": "^5.0.0",
     "react-cosmos-shared2": "^4.8.0-alpha.2",

packages/react-cosmos-shared2/package.json

@@ -5,7 +5,6 @@
   "repository": "https://github.com/react-cosmos/react-cosmos/tree/master/packages/react-cosmos-shared2",
   "license": "MIT",
   "dependencies": {
-    "@babel/runtime-corejs2": "^7.3.1",
     "lodash": "^4.17.11",
     "react-element-to-jsx-string": "^14.0.2",
     "react-is": "^16.8.1"