Fixes for checked mode and change buildbot script to run dart2js tests in checked mode also.

lib/compiler/implementation/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 336 matching lines @@
 
   String visitModulo(HModulo node) => visitInvokeStatic(node);
 
   String visitMultiply(HMultiply node) => visitInvokeStatic(node);
 
   String visitNegate(HNegate node) => visitInvokeStatic(node);
 
   String visitNot(HNot node) => "Not: ${temporaryId(node.inputs[0])}";
 
   String visitParameterValue(HParameterValue node) {
-    return "p${node.element.name.slowToString()}";
+    return "p${node.sourceElement.name.slowToString()}";
   }
 
   String visitPhi(HPhi phi) {
     StringBuffer buffer = new StringBuffer();
     buffer.add("Phi(");
     for (int i = 0; i < phi.inputs.length; i++) {
       if (i > 0) buffer.add(", ");
       buffer.add(temporaryId(phi.inputs[i]));
     }
     buffer.add(")");
@@ skipping 95 matching lines @@
   String visitIs(HIs node) {
     String type = node.typeExpression.toString();
     return "TypeTest: ${temporaryId(node.expression)} is $type";
   }
 
   String visitTypeConversion(HTypeConversion node) {
     String type = node.propagatedType.toString();
     return "TypeConversion: ${temporaryId(node.inputs[0])} to $type";
   }
 }