The decision as to whether to optimize an IIFE as oneshot depends on
whether it's outer scope is the script scope. During lazy compile, we
might have discarded scopes which don't need a context between the IIFE
and the script scope, which means we might treat an IIFE as oneshot,
even though initial eager compile treated it as non-oneshot. Both
bytecode flushing and lazy source positions rely on us generating the
same bytecode during lazy compile as eager compile, so we move the
decision into the parser where it happens once and is then stored in
the SFI for any future lazy compiles.

BUG=v8:8395,v8:8510

Change-Id: I88f1e74ad95d47a2636c393ceb1318d7d610055d
Reviewed-on: https://chromium-review.googlesource.com/c/1421841Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58996}