The yield* statement when used in combination with async iterators is not
supported yet, as that is desugared into a more complex construct that doesn't
offer a good dedicated bytecode to attach the source range information yet.

Note that invocation counts of generator functions are incorrect as they count
each resumption as an individual call. See https://crbug.com/v8/6594.

Bug: v8:6000
Change-Id: I7ac7073473c9b64bb207cdbc4dab083ec1145656
Reviewed-on: https://chromium-review.googlesource.com/582690
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46890}