This reverts commit 83908b86.

Reason for revert: https://ci.chromium.org/p/v8/builders/luci.v8.ci/V8%20Linux%20-%20noi18n%20-%20debug/25074

Original change's description:
> Reland "Extract JSObject class from objects.cc"
> 
> This is a reland of b8c821f4
> 
> Fix: include src/string-stream.h for compile failure
> https://ci.chromium.org/p/v8/builders/luci.v8.ci/V8%20Linux%20-%20builder/39320
> 
> Original change's description:
> > Extract JSObject class from objects.cc
> >
> > I extracted following class member functions to js-objects.cc
> > * JSReceiver
> > * JSObject
> > * JSBoundFunction
> > * JSFunction
> > * JSGlobalObject
> > * JSDate
> > * JSMessageObject
> >
> > Declaration of all above class are in js-objects.h.
> >
> > I also moved AllocationSite::DigestTransitionFeedback used in JSObject::UpdateAllocationSite
> > and ShouldConvertToSlowElements used in JSObject and JSArray
> >
> > This patch makes compile time of objects.cc from 17.6s to 14.1s on Z840 Linux.
> > And js-objects.cc takes 8.69s for compile.
> >
> > Bug: v8:7629
> > Change-Id: I989f22363667445dd28d7f8c06c81ff79d6ed45f
> > Reviewed-on: https://chromium-review.googlesource.com/c/1447916
> > Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
> > Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> > Reviewed-by: Marja Hölttä <marja@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#59288}
> 
> Bug: v8:7629
> Bug: v8:8562
> Change-Id: Iac2227c5f0c5a4072d16814ecae481fb4720e4f5
> Reviewed-on: https://chromium-review.googlesource.com/c/1449951
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#59318}

TBR=marja@chromium.org,mstarzinger@chromium.org,titzer@chromium.org,tikuta@chromium.org

Change-Id: I3260edecb1434bbf9c25d89c9f9a8af02d106855
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7629, v8:8562
Reviewed-on: https://chromium-review.googlesource.com/c/1452096Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59324}