If a function is classed as an IIFE it will be have different bytecode generated
to reduce feedback vector overhead for run-once code. As a result, we need to retain
this information if we are going to lazily compile the bytecode later in order to
get the same result. This is necessary for lazy bytecode flushing and lazy source
positions, both of which need to recompile functions which were previously compiled.

BUG=v8:8395,v8:8510

Change-Id: Ib898868102610216315faa20c9da682f6c523390
Reviewed-on: https://chromium-review.googlesource.com/c/1417636
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58921}