remove unused rollup-plugin-flow dependency (#379)

Author: developit

package.json

@@ -45,6 +45,7 @@
     "@babel/core": "^7.4.4",
     "@babel/plugin-proposal-class-properties": "7.4.4",
     "@babel/plugin-syntax-jsx": "^7.2.0",
+    "@babel/plugin-transform-flow-strip-types": "^7.4.4",
     "@babel/plugin-transform-react-jsx": "^7.3.0",
     "@babel/polyfill": "^7.4.4",
     "@babel/preset-flow": "^7.0.0",
@@ -67,7 +68,6 @@
     "rollup-plugin-bundle-size": "^1.0.1",
     "rollup-plugin-commonjs": "^9.0.0",
     "rollup-plugin-es3": "^1.1.0",
-    "rollup-plugin-flow": "^1.1.1",
     "rollup-plugin-json": "^4.0.0",
     "rollup-plugin-node-resolve": "^4.2.3",
     "rollup-plugin-postcss": "^2.0.3",