cps2js: Fix translation of captured 'this'.

tests/compiler/dart2js/js_backend_cps_ir_closures_test.dart

Index: tests/compiler/dart2js/js_backend_cps_ir_closures_test.dart
diff --git a/tests/compiler/dart2js/js_backend_cps_ir_closures_test.dart b/tests/compiler/dart2js/js_backend_cps_ir_closures_test.dart
index 100f26d79eb995890950454f649aaf15fa1479fb..141fac8c07b95082792512c9f32ce25300eed0f2 100644
--- a/tests/compiler/dart2js/js_backend_cps_ir_closures_test.dart
+++ b/tests/compiler/dart2js/js_backend_cps_ir_closures_test.dart
@@ -117,6 +117,20 @@ function() {
     }
   }
 }"""),
+
+  const TestEntry.forMethod('function(A#b)', """
+class A {
+  a() => 1;
+  b() => () => a();
+}
+main() {
+  print(new A().b()());
+}
+""",
+r"""
+function() {
+  return new V.A_b_closure(this);
+}"""),
 ];
 
 void main() {