Disable reg-exp compilation in background via a flag

runtime/vm/flow_graph.h

 // 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.
 
 #ifndef VM_FLOW_GRAPH_H_
 #define VM_FLOW_GRAPH_H_
 
 #include "vm/bit_vector.h"
 #include "vm/growable_array.h"
 #include "vm/hash_map.h"
@@ skipping 267 matching lines @@
   bool IsCompiledForOsr() const { return graph_entry()->IsCompiledForOsr(); }
 
   static void AddToGuardedFields(ZoneGrowableArray<const Field*>* array,
                                  const Field* field);
   void AddToDeferredPrefixes(ZoneGrowableArray<const LibraryPrefix*>* from);
 
   ZoneGrowableArray<const Field*>* guarded_fields() const {
     return guarded_fields_;
   }
 
-  GrowableArray<const Field*>& deoptimize_dependent_code() {
-    return deoptimize_dependent_code_;
-  }
-
   ZoneGrowableArray<const LibraryPrefix*>* deferred_prefixes() const {
     return deferred_prefixes_;
   }
 
   BitVector* captured_parameters() const {
     return captured_parameters_;
   }
 
   intptr_t inlining_id() const { return inlining_id_; }
   void set_inlining_id(intptr_t value) { inlining_id_ = value; }
@@ skipping 64 matching lines @@
   ConstantInstr* constant_null_;
   ConstantInstr* constant_dead_;
   ConstantInstr* constant_empty_context_;
 
   BlockEffects* block_effects_;
   bool licm_allowed_;
 
   ZoneGrowableArray<BlockEntryInstr*>* loop_headers_;
   ZoneGrowableArray<BitVector*>* loop_invariant_loads_;
   ZoneGrowableArray<const Field*>* guarded_fields_;
-  GrowableArray<const Field*> deoptimize_dependent_code_;
   ZoneGrowableArray<const LibraryPrefix*>* deferred_prefixes_;
   DirectChainedHashMap<ConstantPoolTrait> constant_instr_pool_;
   BitVector* captured_parameters_;
 
   intptr_t inlining_id_;
 };
 
 
 class LivenessAnalysis : public ValueObject {
  public:
@@ skipping 140 matching lines @@
 
  private:
   GrowableArray<Definition*> defs_;
   BitVector* contains_vector_;
 };
 
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_H_