Revert "Enqueue superclasses instead of supertypes."

pkg/compiler/lib/src/resolution/registry.dart

Index: pkg/compiler/lib/src/resolution/registry.dart
diff --git a/pkg/compiler/lib/src/resolution/registry.dart b/pkg/compiler/lib/src/resolution/registry.dart
index 47e5748766d608a6193526ac247775593e18da55..64089c0681d03d461483dff61c449a7f16645320 100644
--- a/pkg/compiler/lib/src/resolution/registry.dart
+++ b/pkg/compiler/lib/src/resolution/registry.dart
@@ -94,8 +94,6 @@ class EagerRegistry implements Registry {
     registerDependency(element);
     world.registerStaticUse(element);
   }
-
-  String toString() => 'EagerRegistry for ${mapping.analyzedElement}';
 }
 
 class ResolutionWorldImpact implements WorldImpact {
@@ -224,8 +222,6 @@ class ResolutionRegistry implements Registry {
 
   Backend get backend => compiler.backend;
 
-  String toString() => 'ResolutionRegistry for ${mapping.analyzedElement}';
-
   //////////////////////////////////////////////////////////////////////////////
   //  Node-to-Element mapping functionality.
   //////////////////////////////////////////////////////////////////////////////