Add a parameter to return continuations

sdk/lib/_internal/compiler/implementation/cps_ir/cps_ir_nodes.dart

Index: sdk/lib/_internal/compiler/implementation/cps_ir/cps_ir_nodes.dart
diff --git a/sdk/lib/_internal/compiler/implementation/cps_ir/cps_ir_nodes.dart b/sdk/lib/_internal/compiler/implementation/cps_ir/cps_ir_nodes.dart
index 957d7a1aa2ac146422a582bc3b78b2a31cb1d430..d0912ef5c30bc55574e45f0c2b459552ec3feb5a 100644
--- a/sdk/lib/_internal/compiler/implementation/cps_ir/cps_ir_nodes.dart
+++ b/sdk/lib/_internal/compiler/implementation/cps_ir/cps_ir_nodes.dart
@@ -493,8 +493,8 @@ class Parameter extends Primitive {
   accept(Visitor visitor) => visitor.visitParameter(this);
 }
 
-/// Continuations are normally bound by 'let cont'.  A continuation with no
-/// parameter (or body) is used to represent a function's return continuation.
+/// Continuations are normally bound by 'let cont'.  A continuation with one
+/// parameter and no body is used to represent a function's return continuation.
 /// The return continuation is bound by the Function, not by 'let cont'.
 class Continuation extends Definition implements InteriorNode {
   final List<Parameter> parameters;
@@ -505,7 +505,7 @@ class Continuation extends Definition implements InteriorNode {
 
   Continuation(this.parameters);
 
-  Continuation.retrn() : parameters = null;
+  Continuation.retrn() : parameters = <Parameter>[new Parameter(null)];
 
   accept(Visitor visitor) => visitor.visitContinuation(this);
 }