Added babel-runtime dependency to deduplicate dependencies when using yarn (#1441)

Author: jkimbo

packages/react-scripts/package.json

@@ -28,6 +28,7 @@
     "babel-eslint": "7.1.1",
     "babel-jest": "18.0.0",
     "babel-loader": "6.2.10",
+    "babel-runtime": "^6.20.0",
     "babel-preset-react-app": "^2.0.1",
     "case-sensitive-paths-webpack-plugin": "1.1.4",
     "chalk": "1.1.3",