Update jestSupport in preparation for upgrading jest to latest version

jestSupport/env.js

@@ -8,6 +8,7 @@
  */
 'use strict';
 
-global.setImmediate = global.setImmediate || function(fn) {
-  return setTimeout(fn, 0);
-};
+window.__DEV__ = true;
+window.Env = {};
+
+require.requireActual('./setupEnvPolyfills');

jestSupport/setupEnvPolyfills.js

@@ -0,0 +1,67 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * This pipes all of our console logging functions to native logging so that
+ * JavaScript errors in required modules show up in Xcode via NSLog.
+ */
+
+'use strict';
+
+// WARNING: This is an optimized version that fails on hasOwnProperty checks
+// and non objects. It's not spec-compliant. It's a perf optimization.
+
+Object.assign = function(target, sources) {
+  if (__DEV__) {
+    if (target == null) {
+      throw new TypeError('Object.assign target cannot be null or undefined');
+    }
+    if (typeof target !== 'object' && typeof target !== 'function') {
+      throw new TypeError(
+        'In this environment the target of assign MUST be an object.' +
+        'This error is a performance optimization and not spec compliant.'
+      );
+    }
+  }
+
+  for (var nextIndex = 1; nextIndex < arguments.length; nextIndex++) {
+    var nextSource = arguments[nextIndex];
+    if (nextSource == null) {
+      continue;
+    }
+
+    if (__DEV__) {
+      if (typeof nextSource !== 'object' &&
+          typeof nextSource !== 'function') {
+        throw new TypeError(
+          'In this environment the target of assign MUST be an object.' +
+          'This error is a performance optimization and not spec compliant.'
+        );
+      }
+    }
+
+    // We don't currently support accessors nor proxies. Therefore this
+    // copy cannot throw. If we ever supported this then we must handle
+    // exceptions and side-effects.
+
+    for (var key in nextSource) {
+      if (__DEV__) {
+        var hasOwnProperty = Object.prototype.hasOwnProperty;
+        if (!hasOwnProperty.call(nextSource, key)) {
+          throw new TypeError(
+            'One of the sources to assign has an enumerable key on the ' +
+            'prototype chain. This is an edge case that we do not support. ' +
+            'This error is a performance optimization and not spec compliant.'
+          );
+        }
+      }
+      target[key] = nextSource[key];
+    }
+  }
+
+  return target;
+};