Revert of [heap] Refactor evacuation for young and old gen into visitors....

Revert of [heap] Refactor evacuation for young and old gen into visitors. (patchset #1 id:1 of https://codereview.chromium.org/1493523003/ )

Reason for revert:
Speculative revert for crashing Canary.

Original issue's description:
> Reland of [heap] Refactor evacuation for young and old gen into visitors. (patchset #1 id:1 of https://codereview.chromium.org/1483393002/ )
>
> Reason for revert:
> Reland after fixing the potential root cause of the canary crasher.
>
> Original issue's description:
> > Revert of [heap] Refactor evacuation for young and old gen into visitors. (patchset #5 id:80001 of https://codereview.chromium.org/1470253002/ )
> >
> > Reason for revert:
> > Still investigating bad canary.
> >
> > Original issue's description:
> > > [heap] Refactor evacuation for young and old gen into visitors.
> > >
> > > Create a visitor for evacuating objects for young and old generation. This is
> > > the first step of preparing a task to process, both,  newspace and oldspace
> > > pages in parallel.
> > >
> > > BUG=chromium:524425
> > > LOG=N
> > >
> > > Committed: https://crrev.com/138d9bae5d7014e0d205634a49b5eac3697744c8
> > > Cr-Commit-Position: refs/heads/master@{#32349}
> >
> > TBR=mlippautz@chromium.org
> > NOPRESUBMIT=true
> > NOTREECHECKS=true
> > NOTRY=true
> > BUG=chromium:524425
> >
> > Committed: https://crrev.com/aa24a3135ec308e1f84bce334844caf0cae2437a
> > Cr-Commit-Position: refs/heads/master@{#32462}
>
> TBR=mlippautz@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=chromium:524425
>
> Committed: https://crrev.com/120b640dfce5f02cecc5af72ca0b2b3b93ce8652
> Cr-Commit-Position: refs/heads/master@{#32500}

TBR=hpayer@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:524425

Review URL: https://codereview.chromium.org/1495583002

Cr-Commit-Position: refs/heads/master@{#32522}

src/heap/mark-compact.h

@@ -314,15 +314,6 @@ class ThreadLocalTop;
 // Mark-Compact collector
 class MarkCompactCollector {
  public:
-  enum IterationMode {
-    kKeepMarking,
-    kClearMarkbits,
-  };
-
-  class EvacuateNewSpaceVisitor;
-  class EvacuateOldSpaceVisitor;
-  class HeapObjectVisitor;
-
   static void Initialize();
 
   void SetUp();
@@ -701,13 +692,14 @@ class MarkCompactCollector {
   // regions to each space's free list.
   void SweepSpaces();
 
-  // Iterates through all live objects on a page using marking information.
-  // Returns whether all objects have successfully been visited.
-  bool IterateLiveObjectsOnPage(MemoryChunk* page, HeapObjectVisitor* visitor,
-                                IterationMode mode);
+  int DiscoverAndEvacuateBlackObjectsOnPage(NewSpace* new_space,
+                                            NewSpacePage* p);
 
   void EvacuateNewSpace();
 
+  bool EvacuateLiveObjectsFromPage(Page* p, PagedSpace* target_space,
+                                   SlotsBuffer** evacuation_slots_buffer);
+
   void AddEvacuationSlotsBufferSynchronized(
       SlotsBuffer* evacuation_slots_buffer);