Revert of GC: Refactor public incremental marking interface in heap (patchset #6 id:100001 of https://codereview.chromium.org/1273483002/ )

Reason for revert:
Fails on the MSAN builder:

http://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20arm64%20-%20sim%20-%20MSAN/builds/3580/steps/Check/logs/RegExpInterruption

Likely due to lack of initialization of IncrementalMarking::gc_callback_flags_.

Original issue's description:
> GC: Refactor incremental marking interface from heap
>
> BUG=
>
> Committed: https://crrev.com/c9fcaeb336919ce4b76fded8c8059457e9820250
> Cr-Commit-Position: refs/heads/master@{#30009}

TBR=ulan@chromium.org,hpayer@chromium.org,mlippautz@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/1271823006

Cr-Commit-Position: refs/heads/master@{#30011}