throw a TypeError if identifier validation fails (#10621)

* throw a TypeError if Identifier validation fails

* Relax identifier validation, reserved words are ok

packages/babel-types/src/definitions/core.js

@@ -1,5 +1,5 @@
 // @flow
-import isValidIdentifier from "../validators/isValidIdentifier";
+import isIdentifierName from "../validators/isIdentifierName";
 
 import {
   BINARY_OPERATORS,
@@ -406,8 +406,8 @@ defineType("Identifier", {
     ...patternLikeCommon,
     name: {
       validate: chain(function(node, key, val) {
-        if (!isValidIdentifier(val)) {
+        if (!isIdentifierName(val)) {
-          // throw new TypeError(`"${val}" is not a valid identifer name`);
+          throw new TypeError(`"${val}" is not a valid identifer name`);
         }
       }, assertValueType("string")),
     },

packages/babel-types/src/index.js

@@ -109,6 +109,7 @@ export {
   default as isValidES3Identifier,
 } from "./validators/isValidES3Identifier";
 export { default as isValidIdentifier } from "./validators/isValidIdentifier";
+export { default as isIdentifierName } from "./validators/isIdentifierName";
 export { default as isVar } from "./validators/isVar";
 export { default as matchesPattern } from "./validators/matchesPattern";
 export { default as validate } from "./validators/validate";

packages/babel-types/src/validators/isIdentifierName.js

@@ -0,0 +1,9 @@
+// @flow
+import esutils from "esutils";
+
+/**
+ * Check if the input `name` is a valid identifier name.
+ */
+export default function isIdentifierName(name: string): boolean {
+  return esutils.keyword.isIdentifierNameES6(name);
+}