Move internal modules to “internal” folder.

.internal/initCloneArray.js

@@ -0,0 +1,23 @@
+/** Used to check objects for own properties. */
+const hasOwnProperty = Object.prototype.hasOwnProperty;
+
+/**
+ * Initializes an array clone.
+ *
+ * @private
+ * @param {Array} array The array to clone.
+ * @returns {Array} Returns the initialized clone.
+ */
+function initCloneArray(array) {
+  const length = array.length;
+  const result = array.constructor(length);
+
+  // Add properties assigned by `RegExp#exec`.
+  if (length && typeof array[0] == 'string' && hasOwnProperty.call(array, 'index')) {
+    result.index = array.index;
+    result.input = array.input;
+  }
+  return result;
+}
+
+export default initCloneArray;