Add missing parent pointers in CopyingVisitor

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 f93296217e9243de5df268bd0a6caa9f25d4332e..aaf7baf8e48ad7012daff9dc7b3365697c78826a 100644
--- a/pkg/compiler/lib/src/cps_ir/cps_ir_nodes.dart
+++ b/pkg/compiler/lib/src/cps_ir/cps_ir_nodes.dart
@@ -2675,6 +2675,7 @@ class CopyingVisitor extends TrampolineRecursiveVisitor {
       assert(_current != null);
       InteriorExpression interior = _current;
       interior.body = body;
+      body.parent = interior;
     }
     _current = body;
   }
@@ -2692,7 +2693,9 @@ class CopyingVisitor extends TrampolineRecursiveVisitor {
       Expression savedFirst = _first;
       _first = _current = null;
       _processBlock(cont.body);
-      _copies[cont].body = _first;
+      Continuation contCopy = _copies[cont];
+      contCopy.body = _first;
+      _first.parent = contCopy;
       _first = savedFirst;
       _current = null;
     });