Don't hold a pointer to parse_info in compilation_info, and instead explicitly
add the fields needed in compiation_info. The intention is to make ParseInfo
only actually needed for parsing, and eventually make it possible to compile
with only a CompileInfo.

BUG=v8:5203

Change-Id: Iecd39245e44c218874401c3991eeaf3ceef2816f
Reviewed-on: https://chromium-review.googlesource.com/595738Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47119}