Remove support for object grouping during Garbage Collection

runtime/vm/scavenger.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_SCAVENGER_H_
 #define VM_SCAVENGER_H_
 
 #include "platform/assert.h"
 #include "platform/utils.h"
 #include "vm/dart.h"
@@ skipping 213 matching lines @@
     kStoreBufferEntries = 0,
     kDataUnused1 = 1,
     kDataUnused2 = 2,
     kToKBAfterStoreBuffer = 3
   };
 
   uword FirstObjectStart() const { return to_->start() | object_alignment_; }
   SemiSpace* Prologue(Isolate* isolate, bool invoke_api_callbacks);
   void IterateStoreBuffers(Isolate* isolate, ScavengerVisitor* visitor);
   void IterateObjectIdTable(Isolate* isolate, ScavengerVisitor* visitor);
-  void IterateRoots(Isolate* isolate,
-                    ScavengerVisitor* visitor,
-                    bool visit_prologue_weak_persistent_handles);
+  void IterateRoots(Isolate* isolate, ScavengerVisitor* visitor);
   void IterateWeakProperties(Isolate* isolate, ScavengerVisitor* visitor);
   void IterateWeakReferences(Isolate* isolate, ScavengerVisitor* visitor);
-  void IterateWeakRoots(Isolate* isolate,
-                        HandleVisitor* visitor,
-                        bool visit_prologue_weak_persistent_handles);
+  void IterateWeakRoots(Isolate* isolate, HandleVisitor* visitor);
   void ProcessToSpace(ScavengerVisitor* visitor);
   uword ProcessWeakProperty(RawWeakProperty* raw_weak,
                             ScavengerVisitor* visitor);
   void Epilogue(Isolate* isolate, SemiSpace* from, bool invoke_api_callbacks);
 
   bool IsUnreachable(RawObject** p);
 
   // During a scavenge we need to remember the promoted objects.
   // This is implemented as a stack of objects at the end of the to space. As
   // object sizes are always greater than sizeof(uword) and promoted objects do
@@ skipping 57 matching lines @@
 
   friend class ScavengerVisitor;
   friend class ScavengerWeakVisitor;
 
   DISALLOW_COPY_AND_ASSIGN(Scavenger);
 };
 
 }  // namespace dart
 
 #endif  // VM_SCAVENGER_H_