This reverts commit 1416d5a5.

Reason for revert: blocks roll https://chromium-review.googlesource.com/c/chromium/src/+/1564550

Original change's description:
> [map] Support in-place field representation changes.
> 
> This adds a new flag --modify-field-representation-inplace (enabled by
> default), which lets the runtime perform field representation changes
> for Smi to Tagged or for HeapObject to Tagged in-place instead of
> creating new maps and marking the previous map tree as deprecated.
> 
> That means we create (a lot) fewer Maps and DescriptorArrays in the
> beginning and also need to self-heal fewer objects later (migrating
> off the deprecated maps). In TurboFan we just take the "field owner
> dependency" whenever we use the field representation, which is very
> similar to what we already do for the field types. That means if we
> change the representation of a field that we used in optimized code,
> we will simply deoptimize that code and have TurboFan potentially
> later optimize it again with the new field representation.
> 
> On the Speedometer2/ElmJS-TodoMVC test, this reduces the total execution
> time from around 415ms to around 352ms, which corresponds to a **15%**
> improvement. The overall Speedometer2 score improves from around 74.1
> to around 78.3 (on local runs with content_shell), corresponding to a
> **5.6%** improvement here. 🎉
> 
> On the CNN desktop browsing story, it seems that we reduce map space
> utilization/fragmentation by about 4-5%. But since we allocate a lot
> less (fewer Maps and DescriptorArrays) we also significantly change
> the GC timing, which heavily influences the results here. So take this
> with a grain of salt. 🤷‍♂️
> 
> Note: For Double fields, this doesn't change anything, meaning they
> still create new maps and deprecate the previous map trees.
> 
> Bug: v8:8749, v8:8865, v8:9114
> Change-Id: I694a53f87ae5caeb868fd98a21809b66d4297d35
> Cq-Include-Trybots: luci.chromium.try:linux-blink-rel
> Doc: http://bit.ly/v8-in-place-field-representation-changes
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1561132
> Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
> Reviewed-by: Igor Sheludko <ishell@chromium.org>
> Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
> Reviewed-by: Georg Neis <neis@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#60764}

TBR=jarin@chromium.org,neis@chromium.org,ishell@chromium.org,bmeurer@chromium.org,verwaest@chromium.org

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

Bug: v8:8749, v8:8865, v8:9114
Change-Id: I666975d08d51bbe7ab4faec9428b9a1f88e9b322
Cq-Include-Trybots: luci.chromium.try:linux-blink-rel
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1564208Reviewed-by: Michael Hablich <hablich@chromium.org>
Commit-Queue: Michael Hablich <hablich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60807}