The spec got rid of `CheckObjectCoercible` a while back, and so should
we. This change is not observable in most of the affected cases since
`ToObject` is up near the top of most Array method algorithms. An
example of an observable effect of this change occurs for the following
input:

    Array.prototype.sort.call(null, 1);

Behavior before applying the patch (incorrect message):

    TypeError: Array.prototype.sort called on null or undefined

Expected behavior:

    TypeError: The comparison function must be either a function or
               undefined

This patch removes `CheckObjectCoercible` and adds tests to ensure the
few observable cases are addressed correctly.

The patch also adds a missing `ToObject(this)` to
`Array.prototype.lastIndexOf` which would otherwise become observable
as a result of `CheckObjectCoercible` being removed.

BUG=v8:3577,v8:6921

Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ia086095076c4bf4d8d58dab26bc28df02994ed01
Reviewed-on: https://chromium-review.googlesource.com/718577Reviewed-by: Adam Klein <adamk@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Mathias Bynens <mathias@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48800}