Fixes babel#7597

Update babel helpers to not require Symbol to exist. We ran into an issue with ie11 where Symbol is not supported. This PR gaurds the usage of Symbol by ensuring that it exists first. There are also changes that allow objects with a length property and array-like objects to work with `iterableToArray`.

packages/babel-helpers/src/helpers.js

@@ -861,8 +861,13 @@ helpers.arrayWithHoles = helper("7.0.0-beta.0")`
 helpers.iterableToArray = helper("7.0.0-beta.0")`
   export default function _iterableToArray(iter) {
     if (
-      Symbol.iterator in Object(iter) ||
-      Object.prototype.toString.call(iter) === "[object Arguments]"
+      Array.isArray(iter)
+      || typeof iter === 'string'
+      || (typeof Symbol === 'function' && Symbol.iterator in Object(iter))
+      || (iter && 'length' in iter)
+      || (typeof Map !== 'undefined' && iter instanceof Map)
+      || (typeof Set !== 'undefined' && iter instanceof Set)
+      || Object.prototype.toString.call(iter) === "[object Arguments]"
     ) return Array.from(iter);
   }
 `;
@@ -1562,7 +1567,9 @@ helpers.decorate = helper("7.1.5")`
       value: "Descriptor",
       configurable: true,
     };
-    Object.defineProperty(obj, Symbol.toStringTag, desc);
+
+    if (typeof Symbol === 'function' && Symbol.toStringTag)
+      Object.defineProperty(obj, Symbol.toStringTag, desc);
 
     if (element.kind === "field") obj.initializer = element.initializer;
 
@@ -1675,7 +1682,9 @@ helpers.decorate = helper("7.1.5")`
     };
 
     var desc = { value: "Descriptor", configurable: true };
-    Object.defineProperty(obj, Symbol.toStringTag, desc);
+
+    if (typeof Symbol === 'function' && Symbol.toStringTag)
+      Object.defineProperty(obj, Symbol.toStringTag, desc);
 
     return obj;
   }

packages/babel-runtime-corejs2/helpers/esm/iterableToArray.js

@@ -1,5 +1,9 @@
 import _Array$from from "../../core-js/array/from";
+import _Set from "../../core-js/set";
+import _Map from "../../core-js/map";
 import _isIterable from "../../core-js/is-iterable";
+import _Symbol from "../../core-js/symbol";
+import _Array$isArray from "../../core-js/array/is-array";
 export default function _iterableToArray(iter) {
-  if (_isIterable(Object(iter)) || Object.prototype.toString.call(iter) === "[object Arguments]") return _Array$from(iter);
+  if (_Array$isArray(iter) || typeof iter === 'string' || typeof _Symbol === 'function' && _isIterable(Object(iter)) || iter && 'length' in iter || typeof _Map !== 'undefined' && iter instanceof _Map || typeof _Set !== 'undefined' && iter instanceof _Set || Object.prototype.toString.call(iter) === "[object Arguments]") return _Array$from(iter);
 }

packages/babel-runtime-corejs2/helpers/iterableToArray.js

@@ -1,9 +1,17 @@
 var _Array$from = require("../core-js/array/from");
 
+var _Set = require("../core-js/set");
+
+var _Map = require("../core-js/map");
+
 var _isIterable = require("../core-js/is-iterable");
 
+var _Symbol = require("../core-js/symbol");
+
+var _Array$isArray = require("../core-js/array/is-array");
+
 function _iterableToArray(iter) {
-  if (_isIterable(Object(iter)) || Object.prototype.toString.call(iter) === "[object Arguments]") return _Array$from(iter);
+  if (_Array$isArray(iter) || typeof iter === 'string' || typeof _Symbol === 'function' && _isIterable(Object(iter)) || iter && 'length' in iter || typeof _Map !== 'undefined' && iter instanceof _Map || typeof _Set !== 'undefined' && iter instanceof _Set || Object.prototype.toString.call(iter) === "[object Arguments]") return _Array$from(iter);
 }
 
 module.exports = _iterableToArray;

packages/babel-runtime/helpers/iterableToArray.js

@@ -1,5 +1,5 @@
 function _iterableToArray(iter) {
-  if (Symbol.iterator in Object(iter) || Object.prototype.toString.call(iter) === "[object Arguments]") return Array.from(iter);
+  if (Array.isArray(iter) || typeof iter === 'string' || typeof Symbol === 'function' && Symbol.iterator in Object(iter) || iter && 'length' in iter || typeof Map !== 'undefined' && iter instanceof Map || typeof Set !== 'undefined' && iter instanceof Set || Object.prototype.toString.call(iter) === "[object Arguments]") return Array.from(iter);
 }
 
 module.exports = _iterableToArray;