Move String interpolation constant folding from constant propagator to canonicalizer

runtime/vm/intermediate_language.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_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 3683 matching lines @@
   intptr_t token_pos() const { return token_pos_; }
 
   virtual CompileType ComputeType() const;
   // Issues a static call to Dart code whihc calls toString on objects.
   virtual EffectSet Effects() const { return EffectSet::All(); }
   virtual bool CanDeoptimize() const { return true; }
   virtual bool MayThrow() const { return true; }
 
   const Function& CallFunction() const;
 
+  virtual Definition* Canonicalize(FlowGraph* flow_graph);
+
   DECLARE_INSTRUCTION(StringInterpolate)
 
  private:
   const intptr_t token_pos_;
   Function& function_;
 
   DISALLOW_COPY_AND_ASSIGN(StringInterpolateInstr);
 };
 
 
@@ skipping 3184 matching lines @@
   ForwardInstructionIterator* current_iterator_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_