dart2js cps: Compute intercepted classes in optimize_interceptors.

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

Index: pkg/compiler/lib/src/cps_ir/backward_null_check_remover.dart
diff --git a/pkg/compiler/lib/src/cps_ir/backward_null_check_remover.dart b/pkg/compiler/lib/src/cps_ir/backward_null_check_remover.dart
index 8a941e70c6aa832bb9e3494b978dae051ce47f26..9daa9acf98c57a14e360a5f827b5de955fcc2ff3 100644
--- a/pkg/compiler/lib/src/cps_ir/backward_null_check_remover.dart
+++ b/pkg/compiler/lib/src/cps_ir/backward_null_check_remover.dart
@@ -1,7 +1,7 @@
 library dart2js.cps_ir.backward_null_check_remover;
 
 import 'cps_ir_nodes.dart';
-import 'optimizers.dart' show Pass;
+import 'optimizers.dart';
 import '../common/names.dart';
 import '../universe/selector.dart';
 import 'type_mask_system.dart';
@@ -59,16 +59,12 @@ class BackwardNullCheckRemover extends BlockVisitor implements Pass {
     if (prim is GetIndex) return prim.object;
     if (prim is SetField) return prim.object;
     if (prim is SetIndex) return prim.object;
-    if (prim is InvokeMethod && !nullSelectors.contains(prim.selector)) {
+    if (prim is InvokeMethod && !selectorsOnNull.contains(prim.selector)) {
       return prim.dartReceiverReference;
     }
     return null;
   }
 
-  static final List<Selector> nullSelectors = <Selector>[
-      Selectors.equals, Selectors.hashCode_, Selectors.noSuchMethod_,
-      Selectors.runtimeType_];
-
   /// It has been determined that the null check in [prim] made redundant by
   /// [newNullCheck].  Eliminate [prim] if it is not needed any more.
   void tryEliminateRedundantNullCheck(Primitive prim, Primitive newNullCheck) {