BytecodeList::New() returns a reference to the BytecodeLabel added to the list.
Since ZoneVector can resize, this reference could become invalid. Instead
move to a ZoneLinkedList so the references never move.

Since we were using zone vectors, the old references were still valid, and
they were only mutated to set is_bound_, so only DCHECKs should have been
affected.

Change-Id: I5da850af2596dcd7f56578a6e5badd332350cb5b
Reviewed-on: https://chromium-review.googlesource.com/544941
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46145}