[react-packager][streamline oss] Move open sourced JS source to react-native-github

Libraries/Utilities/mergeIntoFast.js

@@ -0,0 +1,21 @@
+/**
+ * Copyright 2004-present Facebook. All Rights Reserved.
+ *
+ * @providesModule mergeIntoFast
+ */
+'use strict';
+
+/**
+ * Faster version of `mergeInto` that doesn't check its arguments and
+ * also copies over prototye inherited properties.
+ *
+ * @param {object} one Object to assign to.
+ * @param {object} two Object to assign from.
+ */
+var mergeIntoFast = function(one, two) {
+  for (var keyTwo in two) {
+    one[keyTwo] = two[keyTwo];
+  }
+};
+
+module.exports = mergeIntoFast;