This reverts commit 6c68efac.

Reason for revert: https://bugs.chromium.org/p/v8/issues/detail?id=7668

Original change's description:
> Reland "[heap] Move initial objects into RO_SPACE"
>
> This is a reland of f8ae62fe
>
> Original change's description:
> > [heap] Move initial objects into RO_SPACE
> >
> > This moves:
> > * the main oddballs (null, undefined, hole, true, false) as well as
> > their supporting maps (also adds hole as an internalized string to make
> > this work).
> > * most of the internalized strings
> > * the struct maps
> > * empty array
> > * empty enum cache
> > * the contents of the initial string table
> > * the weak_cell_cache for any map in RO_SPACE (and eagerly creates the
> > value avoid writing to it during run-time)
> >
> > The StartupSerializer stats change as follows:
> >
> >      RO_SPACE  NEW_SPACE  OLD_SPACE  CODE_SPACE  MAP_SPACE  LO_SPACE
> > old         0          0     270264       32608      12144         0
> > new     21776          0     253168       32608       8184         0
> > Overall memory usage has increased by 720 bytes due to the eager
> > initialization of the Map weak cell caches.
> >
> > Also extends --serialization-statistics to print out separate instance
> > type stats for objects in RO_SPACE as shown here:
> >
> >   Read Only Instance types (count and bytes):
> >        404      16736  ONE_BYTE_INTERNALIZED_STRING_TYPE
> >          2         32  HEAP_NUMBER_TYPE
> >          5        240  ODDBALL_TYPE
> >         45       3960  MAP_TYPE
> >          1         16  BYTE_ARRAY_TYPE
> >          1         24  TUPLE2_TYPE
> >          1         16  FIXED_ARRAY_TYPE
> >          1         32  DESCRIPTOR_ARRAY_TYPE
> >         45        720  WEAK_CELL_TYPE
> >
> > Bug: v8:7464
> > Change-Id: I12981c39c82a7057f68bbbe03f89fb57b0b4c6a6
> > Reviewed-on: https://chromium-review.googlesource.com/973722
> > Commit-Queue: Dan Elphick <delphick@chromium.org>
> > Reviewed-by: Hannes Payer <hpayer@chromium.org>
> > Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
> > Reviewed-by: Yang Guo <yangguo@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#52435}
>
> Bug: v8:7464
> Change-Id: I50427edfeb53ca80ec4cf46566368fb2213ccf7b
> Reviewed-on: https://chromium-review.googlesource.com/999654
> Commit-Queue: Dan Elphick <delphick@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Hannes Payer <hpayer@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#52638}

TBR=rmcilroy@chromium.org,yangguo@chromium.org,hpayer@chromium.org,mlippautz@chromium.org,delphick@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: v8:7464,v8:7668
Change-Id: I10aa03623b51e997f95a3715ea9f0bf5d29d2cdb
Reviewed-on: https://chromium-review.googlesource.com/1016600
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52667}