[heap] Remove outdated empty descriptor array marking code.

src/heap/mark-compact.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/heap/mark-compact.h"
 
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/base/sys-info.h"
 #include "src/code-stubs.h"
@@ skipping 1317 matching lines @@
       MarkObject(optimized_code, optimized_code_mark);
     }
   }
 }
 
 
 void MarkCompactCollector::PrepareForCodeFlushing() {
   // If code flushing is disabled, there is no need to prepare for it.
   if (!is_code_flushing_enabled()) return;
 
-  // Ensure that empty descriptor array is marked. Method MarkDescriptorArray
-  // relies on it being marked before any other descriptor array.
-  HeapObject* descriptor_array = heap()->empty_descriptor_array();
-  MarkBit descriptor_array_mark = Marking::MarkBitFrom(descriptor_array);
-  MarkObject(descriptor_array, descriptor_array_mark);
-
   // Make sure we are not referencing the code from the stack.
   DCHECK(this == heap()->mark_compact_collector());
   PrepareThreadForCodeFlushing(heap()->isolate(),
                                heap()->isolate()->thread_local_top());
 
   // Iterate the archived stacks in all threads to check if
   // the code is referenced.
   CodeMarkingVisitor code_marking_visitor(this);
   heap()->isolate()->thread_manager()->IterateArchivedThreads(
       &code_marking_visitor);
@@ skipping 2455 matching lines @@
     MarkBit mark_bit = Marking::MarkBitFrom(host);
     if (Marking::IsBlack(mark_bit)) {
       RelocInfo rinfo(isolate(), pc, RelocInfo::CODE_TARGET, 0, host);
       RecordRelocSlot(host, &rinfo, target);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8