Reuse the top ApiLocalScope so that we do not allocate and free an ApiLocalScope

runtime/vm/handles_impl.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_HANDLES_IMPL_H_
 #define VM_HANDLES_IMPL_H_
 
 #include "vm/heap.h"
 #include "vm/visitor.h"
 
@@ skipping 48 matching lines @@
 
   // Visit all scoped handles.
   block = &first_scoped_block_;
   do {
     block->Visit(visitor);
     block = block->next_block();
   } while (block != NULL);
 }
 
 
+template <int kHandleSizeInWords, int kHandlesPerChunk, int kOffsetOfRawPtr>
+void Handles<kHandleSizeInWords,
+             kHandlesPerChunk,
+             kOffsetOfRawPtr>::Reset() {
+  // Delete all the extra zone handle blocks allocated and reinit the first
+  // zone block.
+  if (zone_blocks_ != NULL) {
+    DeleteHandleBlocks(zone_blocks_->next_block());
+    zone_blocks_->ReInit();
+  }
+
+  // Delete all the extra scoped handle blocks allocated and reinit the first
+  // scoped block.
+  DeleteHandleBlocks(first_scoped_block_.next_block());
+  first_scoped_block_.ReInit();
+  scoped_blocks_ = &first_scoped_block_;
+}
+
+
 // Figure out the current handle scope using the current Isolate and
 // allocate a handle in that scope. The function assumes that a
 // current Isolate, current zone and current handle scope exist. It
 // asserts for this appropriately.
 template <int kHandleSizeInWords, int kHandlesPerChunk, int kOffsetOfRawPtr>
 uword Handles<kHandleSizeInWords,
               kHandlesPerChunk,
               kOffsetOfRawPtr>::AllocateHandle(Isolate* isolate) {
   ASSERT(isolate != NULL);
   ASSERT(isolate->current_zone() != NULL);
@@ skipping 269 matching lines @@
 template <int kHandleSizeInWords, int kHandlesPerChunk, int kOffsetOfRawPtr>
 int Handles<kHandleSizeInWords,
             kHandlesPerChunk,
             kOffsetOfRawPtr>::HandlesBlock::HandleCount() const {
   return (next_handle_slot_ / kHandleSizeInWords);
 }
 
 }  // namespace dart
 
 #endif  // VM_HANDLES_IMPL_H_