Readd Missing raf Package

Author: wmonk

packages/react-scripts/package.json

@@ -36,6 +36,7 @@
  "postcss-flexbugs-fixes": "3.2.0",
  "postcss-loader": "2.0.6",
  "promise": "8.0.1",
+ "raf": "3.4.0",
  "react-dev-utils": "^4.0.1",
  "style-loader": "0.18.2",
  "ts-jest": "^20.0.7",