Ensure references to the room list store are broken for diffing

See commit diff for details.

src/utils/arrays.ts

@@ -14,6 +14,15 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+/**
+ * Clones an array as fast as possible, retaining references of the array's values.
+ * @param a The array to clone. Must be defined.
+ * @returns A copy of the array.
+ */
+export function arrayFastClone(a: any[]): any[] {
+    return a.slice(0, a.length);
+}
+
 /**
  * Determines if the two arrays are different either in length, contents,
  * or order of those contents.