Give a length field to stack bitmaps.

runtime/vm/code_descriptors.cc

 // 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.
 
 #include "vm/code_descriptors.h"
 
 namespace dart {
 
 void DescriptorList::AddDescriptor(PcDescriptors::Kind kind,
                                    intptr_t pc_offset,
@@ skipping 36 matching lines @@
                               DeoptId(i),
                               TokenPos(i),
                               TryIndex(i));
   }
   return descriptors.raw();
 }
 
 
 void StackmapTableBuilder::AddEntry(intptr_t pc_offset,
                                     BitmapBuilder* bitmap) {
-  stack_map_ = Stackmap::New(pc_offset, entry_length_, bitmap);
+  bitmap->SetLength(entry_length_);
+  stack_map_ = Stackmap::New(pc_offset, bitmap);
   list_.Add(stack_map_);
 }
 
 
 bool StackmapTableBuilder::Verify() {
   intptr_t num_entries = Length();
   Stackmap& map1 = Stackmap::Handle();
   Stackmap& map2 = Stackmap::Handle();
   for (intptr_t i = 1; i < num_entries; i++) {
     map1 = MapAt(i - 1);
@@ skipping 23 matching lines @@
 }
 
 
 RawStackmap* StackmapTableBuilder::MapAt(int index) const {
   Stackmap& map = Stackmap::Handle();
   map ^= list_.At(index);
   return map.raw();
 }
 
 }  // namespace dart