Spec: https://tc39.github.io/ecma262/#sec-array.of

Note that the `IsConstructor` abstract operation [1] is implemented
as a `typeswitch`.

[1] https://tc39.github.io/ecma262/#sec-isconstructor

Bug: v8:8321
Change-Id: I17af918c1d928faf8a630b35432876baa96da217
Reviewed-on: https://chromium-review.googlesource.com/c/1296464Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Mathias Bynens <mathias@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56935}