dart2js CPS: Clean up the S-Expression builder.

pkg/compiler/lib/src/js_backend/codegen/task.dart

 // Copyright (c) 2014, 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.
 
 /// Generate code using the cps-based IR pipeline.
 library code_generator_task;
 
 import 'glue.dart';
 import 'codegen.dart';
 import 'unsugar.dart';
@@ skipping 133 matching lines @@
   }
 
   void dumpTypedIR(cps.FunctionDefinition cpsNode,
                    TypePropagator typePropagator) {
     if (PRINT_TYPED_IR_FILTER != null &&
         PRINT_TYPED_IR_FILTER.matchAsPrefix(cpsNode.element.name) != null) {
       String printType(nodeOrRef, String s) {
         cps.Node node = nodeOrRef is cps.Reference
             ? nodeOrRef.definition
             : nodeOrRef;
-        var type = typePropagator.getType(node);
-        return type == null ? s : "$s:${formatTypeMask(type.type)}";
+        return node is cps.Variable && node.type != null
+            ? '$s:${formatTypeMask(node.type)}'
+            : s;
       }
       DEBUG_MODE = true;
       print(new SExpressionStringifier(printType).visit(cpsNode));
     }
   }
 
   static bool checkCpsIntegrity(cps.FunctionDefinition node) {
     new CheckCpsIntegrity().check(node);
     return true; // So this can be used from assert().
   }
@@ skipping 76 matching lines @@
     // TODO(sigurdm): Make a better list of tasks.
     return <CompilerTask>[irBuilderTask]..addAll(fallbackCompiler.tasks);
   }
 
   js.Node attachPosition(js.Node node, AstElement element) {
     return node.withSourceInformation(
         sourceInformationFactory.createBuilderForContext(element)
             .buildDeclaration(element));
   }
 }