Revert of Concurrent sweeping of code space.

src/frames.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/frames.h"
 
 #include <sstream>
 
 #include "src/v8.h"
 
@@ skipping 1413 matching lines @@
   // Check if the inner pointer points into a large object chunk.
   LargePage* large_page = heap->lo_space()->FindPage(inner_pointer);
   if (large_page != NULL) {
     return GcSafeCastToCode(large_page->GetObject(), inner_pointer);
   }
 
   // Iterate through the page until we reach the end or find an object starting
   // after the inner pointer.
   Page* page = Page::FromAddress(inner_pointer);
 
-  page->skip_list()->Lock();
   Address addr = page->skip_list()->StartFor(inner_pointer);
-  page->skip_list()->Unlock();
 
   Address top = heap->code_space()->top();
   Address limit = heap->code_space()->limit();
 
   while (true) {
     if (addr == top && addr != limit) {
       addr = limit;
       continue;
     }
 
@@ skipping 91 matching lines @@
   for (StackFrameIterator it(isolate); !it.done(); it.Advance()) {
     StackFrame* frame = AllocateFrameCopy(it.frame(), zone);
     list.Add(frame, zone);
   }
   return list.ToVector();
 }
 
 
 }  // namespace internal
 }  // namespace v8