Remove "--optional runtime" that was dropped in Babel v6 (#1485)

Author: IvanGoncharov

package.json

@@ -34,8 +34,8 @@
     "build:clean": "rm -rf ./dist && mkdir ./dist",
     "build:cp": "cp README.md LICENSE ./dist",
     "build:package-json": "node ./resources/copy-package-json.js",
-    "build:cjs": "babel src --optional runtime --ignore '**/__tests__' --out-dir dist/",
-    "build:mjs": "BABEL_MODULES=1 babel src --optional runtime --ignore '**/__tests__' --out-dir dist/module/ && for file in $(find dist/module -name '*.js'); do mv \"$file\" `echo \"$file\" | sed 's/dist\\/module/dist/g; s/.js$/.mjs/g'`; done && rm -rf dist/module",
+    "build:cjs": "babel src --ignore '**/__tests__' --out-dir dist/",
+    "build:mjs": "BABEL_MODULES=1 babel src --ignore '**/__tests__' --out-dir dist/module/ && for file in $(find dist/module -name '*.js'); do mv \"$file\" `echo \"$file\" | sed 's/dist\\/module/dist/g; s/.js$/.mjs/g'`; done && rm -rf dist/module",
     "build:flow": "for file in $(find ./src -name '*.js' -not -path '*/__tests__*'); do cp \"$file\" `echo \"$file\" | sed 's/\\/src\\//\\/dist\\//g'`.flow; done",
     "preversion": ". ./resources/checkgit.sh && npm test",
     "prepublishOnly": ". ./resources/prepublish.sh",

resources/benchmark.js

@@ -13,7 +13,7 @@ const fs = require('fs');
 const path = require('path');
 
 // Like build:cjs, but includes __tests__ and copies other files.
-const BUILD_CMD = 'babel src --optional runtime --copy-files --out-dir dist/';
+const BUILD_CMD = 'babel src --copy-files --out-dir dist/';
 const LOCAL = 'local';
 function LOCAL_DIR(...paths) {
   return path.join(__dirname, '..', ...paths);