dart2js cps: Cleanup type annotations in type propagation and remove code to handle null continuati…

pkg/compiler/lib/src/cps_ir/cps_ir_tracer.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.
 
 library dart2js.ir_tracer;
 
 import 'dart:async' show EventSink;
 import 'cps_ir_nodes.dart' as cps_ir hide Function;
 import '../tracer.dart';
 
@@ skipping 347 matching lines @@
   visitApplyBuiltinOperator(cps_ir.ApplyBuiltinOperator node) {
     String operator = node.operator.toString();
     String args = node.arguments.map(formatReference).join(', ');
     return 'ApplyBuiltinOperator $operator ($args)';
   }
 
   @override
   visitForeignCode(cps_ir.ForeignCode node) {
     String id = names.name(node);
     String arguments = node.arguments.map(formatReference).join(', ');
-    String continuation = node.continuation == null ? ''
-        : ' ${formatReference(node.continuation)}';
+    String continuation = formatReference(node.continuation);
     printStmt(id, "ForeignCode ${node.type} ${node.codeTemplate.source} "
         "$arguments $continuation");
   }
 
   visitGetLength(cps_ir.GetLength node) {
     String object = formatReference(node.object);
     return 'GetLength $object';
   }
 
   visitGetIndex(cps_ir.GetIndex node) {
@@ skipping 274 matching lines @@
   visitSetField(cps_ir.SetField node) {
     unexpectedNode(node);
   }
 
   visitSetStatic(cps_ir.SetStatic node) {
     unexpectedNode(node);
   }
 
   @override
   visitForeignCode(cps_ir.ForeignCode node) {
-    if (node.continuation != null) {
-      addEdgeToContinuation(node.continuation);
-    }
+    addEdgeToContinuation(node.continuation);
   }
 }