Fix printing of HConstant

pkg/compiler/lib/src/ssa/nodes.dart

 // 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.
 
 part of ssa;
 
 abstract class HVisitor<R> {
   R visitAdd(HAdd node);
   R visitAwait(HAwait node);
   R visitBitAnd(HBitAnd node);
@@ skipping 2039 matching lines @@
       : super(<HInstruction>[condition]);
   toString() => 'loop-branch';
   accept(HVisitor visitor) => visitor.visitLoopBranch(this);
 }
 
 class HConstant extends HInstruction {
   final ConstantValue constant;
   HConstant.internal(this.constant, TypeMask constantType)
       : super(<HInstruction>[], constantType);
 
-  toString() => 'literal: $constant';
+  toString() => 'literal: ${constant.toStructuredString()}';
   accept(HVisitor visitor) => visitor.visitConstant(this);
 
   bool isConstant() => true;
   bool isConstantBoolean() => constant.isBool;
   bool isConstantNull() => constant.isNull;
   bool isConstantNumber() => constant.isNum;
   bool isConstantInteger() => constant.isInt;
   bool isConstantString() => constant.isString;
   bool isConstantList() => constant.isList;
   bool isConstantMap() => constant.isMap;
@@ skipping 1060 matching lines @@
 class HDynamicType extends HRuntimeType {
   HDynamicType(DynamicType dartType, TypeMask instructionType)
       : super(const <HInstruction>[], dartType, instructionType);
 
   accept(HVisitor visitor) => visitor.visitDynamicType(this);
 
   int typeCode() => HInstruction.DYNAMIC_TYPE_TYPECODE;
 
   bool typeEquals(HInstruction other) => other is HDynamicType;
 }