RFC: Do not include package-local polyfills.

docs/modern/Introduction.md

@@ -48,6 +48,32 @@ Run the Relay Compiler after making changes to any GraphQL in your Relay applica
 Then after making edits to your application files, just run `yarn run relay` to generate new files, or `yarn run relay -- --watch` to run the compiler as a long-lived process which automatically generates new files whenever you save.
 
 
+## JavaScript environment requirements
+
+The Relay Modern packages distributed on NPM use the widely-supported ES5
+version of JavaScript to support as many browser environments as possible.
+
+However, Relay Modern expects modern JavaScript global types (`Map`, `Set`,
+`Promise`, `Object.assign`) to be defined. If you support older browsers and
+devices which may not yet provide these natively, consider including a global
+polyfill in your bundled application, such as [core-js][] or
+[babel-polyfill](https://babeljs.io/docs/usage/polyfill/).
+
+A polyfilled environment for Relay using [core-js][] to support older browsers
+might look like:
+
+```js
+require('core-js/es6/map');
+require('core-js/es6/set');
+require('core-js/es6/promise');
+require('core-js/es6/object');
+
+require('./myRelayApplication');
+```
+
+[core-js]: https://github.com/zloirock/core-js
+
+
 ## Migrating to Relay Modern
 
 Migrating a Relay Classic app to Relay Modern doesn't require rewriting from

gulpfile.js

@@ -15,18 +15,6 @@ const babelOptions = require('./scripts/getBabelOptions')({
     'babel-core': 'babel-core',
     'babel-generator': 'babel-generator',
     'babel-polyfill': 'babel-polyfill',
-    'babel-runtime/core-js/array/from': 'babel-runtime/core-js/array/from',
-    'babel-runtime/core-js/json/stringify': 'babel-runtime/core-js/json/stringify',
-    'babel-runtime/core-js/map': 'babel-runtime/core-js/map',
-    'babel-runtime/core-js/object/assign': 'babel-runtime/core-js/object/assign',
-    'babel-runtime/core-js/object/freeze': 'babel-runtime/core-js/object/freeze',
-    'babel-runtime/core-js/object/get-own-property-names': 'babel-runtime/core-js/object/get-own-property-names',
-    'babel-runtime/core-js/object/is-frozen': 'babel-runtime/core-js/object/is-frozen',
-    'babel-runtime/core-js/object/keys': 'babel-runtime/core-js/object/keys',
-    'babel-runtime/core-js/object/values': 'babel-runtime/core-js/object/values',
-    'babel-runtime/core-js/promise': 'fbjs/lib/Promise',
-    'babel-runtime/core-js/set': 'babel-runtime/core-js/set',
-    'babel-runtime/core-js/weak-map': 'babel-runtime/core-js/weak-map',
     'babel-runtime/helpers/asyncToGenerator': 'babel-runtime/helpers/asyncToGenerator',
     'babel-runtime/helpers/classCallCheck': 'babel-runtime/helpers/classCallCheck',
     'babel-runtime/helpers/defineProperty': 'babel-runtime/helpers/defineProperty',
@@ -42,6 +30,7 @@ const babelOptions = require('./scripts/getBabelOptions')({
     'fb-watchman': 'fb-watchman',
     'fs': 'fs',
     'graphql': 'graphql',
+    'immutable': 'immutable',
     'net': 'net',
     'path': 'path',
     'prop-types': 'prop-types',
@@ -56,7 +45,7 @@ const babelOptions = require('./scripts/getBabelOptions')({
   },
   plugins: [
     'transform-flow-strip-types',
-    'transform-runtime',
+    ['transform-runtime', {'polyfill': false}],
   ],
   postPlugins: [
     'transform-async-to-generator',

packages/react-relay/classic/ReactRelayClassicExports.js

@@ -17,14 +17,21 @@ const RelayDefaultNetworkLayer = require('RelayDefaultNetworkLayer');
 const RelayPublic = require('RelayPublic');
 const RelayStore = require('RelayStore');
 
-const warning = require('warning');
-
+// As early as possible, check for the existence of the JavaScript globals which
+// React Relay relies upon, and produce a clear message if they do not exist.
 if (__DEV__) {
-  warning(
-    typeof Promise === 'function' && Array.prototype.find,
-    'Relay relies on polyfills for ES6 features in older browsers. ' +
-      'Babel provides a good one: https://babeljs.io/docs/usage/polyfill/',
-  );
+  if (
+    typeof Map !== 'function' ||
+    typeof Set !== 'function' ||
+    typeof Promise !== 'function' ||
+    typeof Object.assign !== 'function' ||
+    typeof Array.prototype.find !== 'function'
+  ) {
+    throw new Error(
+      'react-relay requires Map, Set, Promise, Object.assign, and Array#find ' +
+        'to exist. Use a polyfill to provide these for older browsers.',
+    );
+  }
 }
 
 // By default, assume that GraphQL is served at `/graphql` on the same domain.

packages/relay-runtime/RelayRuntime.js

@@ -35,6 +35,22 @@ export type {
   ConcreteFragment,
 } from 'RelayConcreteNode';
 
+// As early as possible, check for the existence of the JavaScript globals which
+// Relay Runtime relies upon, and produce a clear message if they do not exist.
+if (__DEV__) {
+  if (
+    typeof Map !== 'function' ||
+    typeof Set !== 'function' ||
+    typeof Promise !== 'function' ||
+    typeof Object.assign !== 'function'
+  ) {
+    throw new Error(
+      'relay-runtime requires Map, Set, Promise, and Object.assign to exist. ' +
+        'Use a polyfill to provide these for older browsers.',
+    );
+  }
+}
+
 /**
  * The public interface to Relay Runtime.
  */

scripts/getBabelOptions.js

@@ -19,11 +19,11 @@ module.exports = function(options) {
   }, options);
 
   const fbjsPreset = require('babel-preset-fbjs/configure')({
-    autoImport: true,
+    autoImport: options.autoImport || false,
+    objectAssign: false,
     inlineRequires: true,
     rewriteModules: {
       map: assign({},
-        require('fbjs-scripts/third-party-module-map'),
         require('fbjs/module-map'),
         options.moduleMap
       ),

scripts/jest/preprocessor.js

@@ -21,7 +21,10 @@ const SCHEMA_PATH = path.resolve(__dirname, '../../packages/relay-compiler/testu
 
 const babelOptions = getBabelOptions({
   env: 'test',
+  // Tests use a Promise polfill so they can use jest.runAllTimers().
+  autoImport: true,
   moduleMap: {
+    'immutable': 'immutable',
     'React': 'react',
     'reactComponentExpect': 'react-dom/lib/reactComponentExpect',
     'ReactDOM': 'react-dom',