setup the babel plugin to transform the babel-polyfill calls + pass the data option to the plugin from the preset

experimental/babel-preset-env/src/index.js

@@ -1,4 +1,5 @@
 import pluginList from "../data/plugins.json";
+import builtInsList from "../data/builtIns.json";
 import browserslist from "browserslist";
 import transformPolyfillRequirePlugin from "./transformPolyfillRequirePlugin";
 
@@ -146,6 +147,14 @@ export default function buildPreset(context, opts = {}) {
   let transformations = Object.keys(pluginList)
     .filter((pluginName) => isPluginRequired(targets, pluginList[pluginName]));
 
+  let polyfills;
+  if (useBuiltIns) {
+    polyfills = Object.keys(builtInsList)
+      .filter((builtInName) => isPluginRequired(targets, builtInsList[builtInName]));
+    console.log(polyfills);
+    console.log(polyfills.length, Object.keys(builtInsList).length);
+  }
+
   if (debug && !hasBeenLogged) {
     hasBeenLogged = true;
 
@@ -182,7 +191,7 @@ export default function buildPreset(context, opts = {}) {
     plugins: [
       ...modules,
       ...transformations,
-      // useBuiltIns && transformPolyfillRequirePlugin
-    ]
+      useBuiltIns === true && [transformPolyfillRequirePlugin, { polyfills }]
+    ].filter(Boolean)
   };
 }

experimental/babel-preset-env/src/transformPolyfillRequirePlugin.js

@@ -1,12 +1,66 @@
-export default function (babel) {
-  const { types: t } = babel;
+// Should throw if no babel-polyfill import is found in all files
+// or if more than one is found
+
+// const builtIns = require('../data/builtIns.json');
+const builtIns = {
+  "typed/int8-array": {
+    "chrome": 5,
+    "opera": 12,
+    "firefox": 4,
+    "safari": 5,
+    "node": 0.12,
+    "ie": 10,
+    "android": 4,
+    "ios": 6
+  }
+};
+
+const polyfillSource = "babel-polyfill";
+let numPolyfillImports = 0;
+
+export default function ({ types: t }) {
+  function checkNumPolyfillImports() {
+    numPolyfillImports++;
+    if (numPolyfillImports > 1) {
+      console.log("multiple babel-polyfill imports found");
+      //throw new Error("multiple babel-polyfill imports found");
+    }
+  }
+
+  function isRequire(path, source) {
+    return t.isExpressionStatement(path.node) &&
+      t.isCallExpression(path.node.expression) &&
+      t.isIdentifier(path.node.expression.callee) &&
+      path.node.expression.callee.name === "require" &&
+      path.node.expression.arguments.length === 1 &&
+      t.isStringLiteral(path.node.expression.arguments[0]) &&
+      path.node.expression.arguments[0].value === source;
+  }
+
+  const isPolyfillImport = {
+    ImportDeclaration(path, state) {
+      if (path.node.specifiers.length === 0 &&
+          path.node.source.value === polyfillSource) {
+        checkNumPolyfillImports();
+
+        // change
+        // path.node.source.value = "changed";
+      }
+    },
+    Program(path, state) {
+      path.get("body").forEach((bodyPath) => {
+        if (isRequire(bodyPath, polyfillSource)) {
+          checkNumPolyfillImports();
+
+          // change
+          // bodyPath.node.expression.arguments[0].value = "changed";
+        }
+      });
+    }
+  };
 
   return {
     name: "ast-transform", // not required
-    visitor: {
-      Identifier(path) {
-
-      }
-    }
+    visitor: isPolyfillImport
   };
 }

experimental/babel-preset-env/test/fixtures/preset-options/use-builtins-chrome-55/actual.js

@@ -0,0 +1 @@
+1 ** 2;

experimental/babel-preset-env/test/fixtures/preset-options/use-builtins-chrome-55/expected.js

@@ -0,0 +1 @@
+1 ** 2;

experimental/babel-preset-env/test/fixtures/preset-options/use-builtins-chrome-55/options.json

@@ -0,0 +1,11 @@
+{
+  "presets": [
+    ["../../../../lib", {
+      "targets": {
+        "chrome": 54
+      },
+      "modules": false,
+      "useBuiltIns": true
+    }]
+  ]
+}