dart2js cps: Store the TypeMask for each primitive in a field.

pkg/compiler/lib/src/cps_ir/redundant_join.dart

 // Copyright (c) 2015, 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 dart2js.cps_ir.redundant_join_elimination;
 
 import 'cps_ir_nodes.dart';
 import 'optimizers.dart';
 
 /// Eliminates redundant join points.
@@ skipping 230 matching lines @@
 
     // Create new parameters and update the environment.
     for (int i = 0; i < cont.parameters.length; ++i) {
       Parameter param = cont.parameters[i];
       shadowedKeys.add(param);
       shadowedValues.add(renaming.remove(param));
       // If the parameter appears to belong to another continuation,
       // create a new parameter object for this continuation.
       if (param.parent != cont) {
         Parameter newParam = new Parameter(param.hint);
+        newParam.type = param.type;
         renaming[param] = newParam;
         cont.parameters[i] = newParam;
         newParam.parent = cont;
       }
     }
 
     pushAction(() {
       // Restore the original environment.
       for (int i = 0; i < cont.parameters.length; ++i) {
         renaming.remove(cont.parameters[i]);
         if (shadowedValues[i] != null) {
           renaming[shadowedKeys[i]] = shadowedValues[i];
         }
       }
     });
   }
 
   processReference(Reference ref) {
     Parameter target = renaming[ref.definition];
     if (target != null) {
       ref.changeTo(target);
     }
   }
 }