dart2js cps: Fix a couple of minor issues.

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

 // Copyright (c) 2013, 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.ir_nodes;
 
 import '../constants/expressions.dart';
 import '../constants/values.dart' as values show ConstantValue;
 import '../dart_types.dart' show DartType, InterfaceType, TypeVariableType;
 import '../elements/elements.dart';
 import '../io/source_information.dart' show SourceInformation;
@@ skipping 271 matching lines @@
 /// there is used by optimization passes. This is likely to change.
 class InvokeMethod extends Expression implements Invoke {
   Reference<Primitive> receiver;
   Selector selector;
   TypeMask mask;
   final List<Reference<Primitive>> arguments;
   final Reference<Continuation> continuation;
   final SourceInformation sourceInformation;
 
   /// If true, it is known that the receiver cannot be `null`.
-  ///
-  /// This field is `null` until initialized by optimization phases.
-  bool receiverIsNotNull;
+  bool receiverIsNotNull = false;

[asgerf, 2015/06/29 14:09:12]

The tree builder expects this to be set, but it's nice to be able to run without
optimizations enabled.

 
   InvokeMethod(Primitive receiver,
                this.selector,
                this.mask,
                List<Primitive> arguments,
                Continuation continuation,
                {this.sourceInformation})
       : this.receiver = new Reference<Primitive>(receiver),
         this.arguments = _referenceList(arguments),
         this.continuation = new Reference<Continuation>(continuation);
@@ skipping 966 matching lines @@
   const RemovalVisitor();
 
   processReference(Reference reference) {
     reference.unlink();
   }
 
   static void remove(Node node) {
     (const RemovalVisitor()).visit(node);
   }
 }