Add browser versions of the transform files.

packages/babel-core/package.json

@@ -22,7 +22,9 @@
     "compiler"
   ],
   "browser": {
-    "./lib/config/loading/files/index.js": "./lib/config/loading/files/index-browser.js"
+    "./lib/config/loading/files/index.js": "./lib/config/loading/files/index-browser.js",
+    "./lib/transform-file.js": "./lib/transform-file-browser.js",
+    "./lib/transform-file-sync.js": "./lib/transform-file-sync-browser.js"
   },
   "dependencies": {
     "babel-code-frame": "7.0.0-beta.2",

packages/babel-core/src/transform-file-browser.js

@@ -0,0 +1,14 @@
+// @flow
+import type { FileResult } from "./transformation";
+
+export default function transformFile(
+  filename: string,
+  opts?: Object = {},
+  callback: (?Error, FileResult | null) => void,
+) {
+  if (typeof opts === "function") {
+    callback = opts;
+  }
+
+  callback(new Error("Transforming files is not supported in browsers"), null);
+}

packages/babel-core/src/transform-file-sync-browser.js

@@ -0,0 +1,5 @@
+// @flow
+
+export default function transformFileSync() {
+  throw new Error("Transforming files is not supported in browsers");
+}