dart2js cps: Fix a couple of minor issues.

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

Index: pkg/compiler/lib/src/cps_ir/cps_ir_nodes.dart
diff --git a/pkg/compiler/lib/src/cps_ir/cps_ir_nodes.dart b/pkg/compiler/lib/src/cps_ir/cps_ir_nodes.dart
index fa33169e49131d1bb5d9a976f7a9d912d7e48672..7d8a73d7bfcfa1d605a8d079a1bf56840a574472 100644
--- a/pkg/compiler/lib/src/cps_ir/cps_ir_nodes.dart
+++ b/pkg/compiler/lib/src/cps_ir/cps_ir_nodes.dart
@@ -289,9 +289,7 @@ class InvokeMethod extends Expression implements Invoke {
   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,