Revert "Oilpan: Immediatelly promptly free objects."

This reverts commit f9a22f3e9d081a64e311116662fbdcab90cc4aac.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> Oilpan: Immediatelly promptly free objects.
> 
> This CL brings the following changes to promptly freeing and coalescing:
> 1) Promptly freed objects on already swept pages are immediately added to the free list.
> 2) For promptly freed objects on not already swept pages we only clear the mark bit.
> 3) The promptly_freed_size_ counter is explicitly set to 0 before sweeping because sweeping will take care of coalescing as well.
> 4) The dead bit is removed.
> Note that coalescing before sweeping completed can not happen.
> 
> Future outlook: As a next step we will evaluate if we need coalescing and if we need it we have to make it jank friendly.
> 
> Bug: chromium:804279, chromium:633030
> Change-Id: I35dfae80ae0e7ed6cfbc91877d97d0b5fc26498e
> Reviewed-on: https://chromium-review.googlesource.com/873974
> Commit-Queue: Hannes Payer <hpayer@chromium.org>
> Reviewed-by: Kentaro Hara <haraken@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#532509}

TBR=haraken@chromium.org,hpayer@chromium.org,mlippautz@chromium.org

Change-Id: I868bc9b51c18a546994de93a3a8ef80362b0ba19
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:804279, chromium:633030
Reviewed-on: https://chromium-review.googlesource.com/891640
Reviewed-by: Samuel Huang <huangs@chromium.org>
Commit-Queue: Samuel Huang <huangs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532528}
2 files changed