Make background optimized compilation default true

runtime/vm/code_generator.cc

 // Copyright (c) 2013, 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_generator.h"
 
 #include "vm/assembler.h"
 #include "vm/ast.h"
 #include "vm/code_patcher.h"
 #include "vm/compiler.h"
@@ skipping 12 matching lines @@
 #include "vm/stack_frame.h"
 #include "vm/symbols.h"
 #include "vm/thread_registry.h"
 #include "vm/verifier.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, deoptimize_alot, false,
     "Deoptimizes all live frames when we are about to return to Dart code from"
     " native entries.");
-DEFINE_FLAG(bool, background_compilation, false,
+DEFINE_FLAG(bool, background_compilation, true,
     "Run optimizing compilation in background");
 DEFINE_FLAG(int, max_subtype_cache_entries, 100,
     "Maximum number of subtype cache entries (number of checks cached).");
 DEFINE_FLAG(int, optimization_counter_threshold, 30000,
     "Function's usage-counter value before it is optimized, -1 means never");
 DEFINE_FLAG(int, regexp_optimization_counter_threshold, 1000,
     "RegExp's usage-counter value before it is optimized, -1 means never");
 DEFINE_FLAG(charp, optimization_filter, NULL, "Optimize only named function");
 DEFINE_FLAG(int, reoptimization_counter_threshold, 4000,
     "Counter threshold before a function gets reoptimized.");
@@ skipping 1844 matching lines @@
   const intptr_t elm_size = old_data.ElementSizeInBytes();
   const TypedData& new_data =
       TypedData::Handle(TypedData::New(cid, new_size, Heap::kOld));
   TypedData::Copy(new_data, 0, old_data, 0, old_size * elm_size);
   typed_data_cell.SetAt(0, new_data);
   arguments.SetReturn(new_data);
 }
 
 
 }  // namespace dart