Make string juxtaposition combine properly with string interpolations.

frog/leg/ssa/nodes.dart

 // Copyright (c) 2011, 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.
 
 interface HVisitor<R> {
   R visitAdd(HAdd node);
   R visitBailoutTarget(HBailoutTarget node);
   R visitBitAnd(HBitAnd node);
   R visitBitNot(HBitNot node);
   R visitBitOr(HBitOr node);
@@ skipping 1388 matching lines @@
       DartString leftString = op1.constant.value;
       DartString otherString = null;
       if (right.isConstantString()) {
         otherString = op2.constant.value;
       } else {
         assert(op2.isConstantNumber() ||
                op2.isConstantBoolean() ||
                op2.isConstantNull());
         otherString = new DartString.literal(op2.constant.value.toString());
       }
-      DartString cons = new ConsDartString(leftString, otherString);
+      DartString cons = new DartString.cons(leftString, otherString);
       return graph.addConstantString(cons);
     }
     return super.fold(graph);
   }
 
   String operationAsString() => "+";
   int typeCode() => 5;
   bool typeEquals(other) => other is HAdd;
   bool dataEquals(HInstruction other) => true;
 }
@@ skipping 744 matching lines @@
 class HIfBlockInformation {
   final HIf branch;
   final SubGraph thenGraph;
   final SubGraph elseGraph;
   final HBasicBlock joinBlock;
   HIfBlockInformation(this.branch,
                       this.thenGraph,
                       this.elseGraph,
                       this.joinBlock);
 }