Add new style of string interpolation optimization: new nodes, working constant folding.

runtime/vm/flow_graph_optimizer.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_FLOW_GRAPH_OPTIMIZER_H_
 #define VM_FLOW_GRAPH_OPTIMIZER_H_
 
 #include "vm/intermediate_language.h"
 #include "vm/flow_graph.h"
 
@@ skipping 275 matching lines @@
   }
   bool IsConstant(const Object& value) {
     return !IsNonConstant(value) && !IsUnknown(value);
   }
 
   void HandleBinaryOp(Definition* instr,
                       Token::Kind op_kind,
                       const Value& left,
                       const Value& right);
 
-  void RemoveInterpolationInputs(const StaticCallInstr& call);
-
   virtual void VisitBlocks() { UNREACHABLE(); }
 
 #define DECLARE_VISIT(type) virtual void Visit##type(type##Instr* instr);
   FOR_EACH_INSTRUCTION(DECLARE_VISIT)
 #undef DECLARE_VISIT
 
   FlowGraph* graph_;
 
   // Sentinels for unknown constant and non-constant values.
   const Object& unknown_;
@@ skipping 76 matching lines @@
 // Optimize spill stores inside try-blocks by identifying values that always
 // contain a single known constant at catch block entry.
 class TryCatchAnalyzer : public AllStatic {
  public:
   static void Optimize(FlowGraph* flow_graph);
 };
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_OPTIMIZER_H_