Reapply "Refactor constant part." (r4958) with fixes.

frog/leg/ssa/tracer.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.
 
 #library('tracer');
 
 #import('dart:io');
 #import('ssa.dart');
 #import('../leg.dart');
 
@@ skipping 199 matching lines @@
   }
 
   String visitBreak(HBreak node) {
     HBasicBlock target = currentBlock.successors[0];
     if (node.label !== null) {
       return "Break ${node.label.slowToString()}: (B${target.id})";
     }
     return "Break: (B${target.id})";
   }
 
+  String visitConstant(HConstant constant) => "Constant ${constant.constant}";
+
   String visitDivide(HDivide node) => visitInvokeStatic(node);
 
   String visitEquals(HEquals node) => visitInvokeStatic(node);
 
   String visitExit(HExit node) => "exit";
 
   String visitFieldGet(HFieldGet node) {
     return 'get ${node.element.name.slowToString()}';
   }
 
@@ skipping 90 matching lines @@
 
   String visitForeignNew(HForeignNew node) {
     return visitGenericInvoke("New",
                               "${node.element.name.slowToString()}",
                               node.inputs);
   }
 
   String visitLess(HLess node) => visitInvokeStatic(node);
   String visitLessEqual(HLessEqual node) => visitInvokeStatic(node);
 
-  String visitLiteral(HLiteral literal) => "Literal ${literal.value}";
-
   String visitLiteralList(HLiteralList node) {
     StringBuffer elementsString = new StringBuffer();
     for (int i = 0; i < node.inputs.length; i++) {
       if (i != 0) elementsString.add(", ");
       elementsString.add(temporaryId(node.inputs[i]));
     }
     return "Literal list: [$elementsString]";
   }
 
   String visitLoad(HLoad node) => "Load: ${temporaryId(node.inputs[0])}";
@@ skipping 101 matching lines @@
       default: unreachable();
     }
     return "TypeGuard: ${temporaryId(node.inputs[0])} is $type";
   }
 
   String visitIs(HIs node) {
     String type = node.typeExpression.toString();
     return "TypeTest: ${temporaryId(node.expression)} is $type";
   }
 }