As per (https://github.com/tc39/proposal-string-matchall/pull/41), String.p.matchAll's fallback was removed.
Additionally, removed a IsNullOrUndefined check that was already covered by MaybeCallFunctionAtSymbol.
Updates to Test262 has been submitted: https://github.com/tc39/test262/pull/1990

Bug: v8:6890
Change-Id: I246cbbcb4641ebded704c5f772809f182deaa30e
Reviewed-on: https://chromium-review.googlesource.com/c/1369091
Commit-Queue: Peter Wong <peter.wm.wong@gmail.com>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Mathias Bynens <mathias@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58172}