Reason for revert:
doesn't compile on ToT
Original issue's description:
> Reland: [Parse] ParseInfo owns the parsing Zone.
>
> Moves ownership of the parsing Zone to ParseInfo with a shared_ptr. This is
> in preperation for enabling background compilation jobs for inner functions
> share the AST in the outer-function's parse zone memory (read-only), with the
> and zone being released when all compilation jobs have completed.
>
> BUG=v8:5203,v8:5215
>
> Review-Url: https://codereview.chromium.org/2632123006
> Cr-Commit-Position: refs/heads/master@{#42993}
> Committed: 14fb337200TBR=marja@chromium.org,mstarzinger@chromium.org,ahaas@chromium.org,verwaest@chromium.org,rmcilroy@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:5203,v8:5215
Review-Url: https://codereview.chromium.org/2685543003
Cr-Commit-Position: refs/heads/master@{#42994}
8f4c4233dc