Revert "Normalize type masks to use the least upper instantiated subclass/type."

pkg/compiler/lib/src/closure.dart

Index: pkg/compiler/lib/src/closure.dart
diff --git a/pkg/compiler/lib/src/closure.dart b/pkg/compiler/lib/src/closure.dart
index 9b9d6033050d4cb6963d0dc2d5f86ff202e90d93..00cb34ca1a62dca2496e1f335ff3f9d295c8ab1c 100644
--- a/pkg/compiler/lib/src/closure.dart
+++ b/pkg/compiler/lib/src/closure.dart
@@ -998,9 +998,6 @@ class ClosureTranslator extends Visitor {
     String closureName = computeClosureName(element);
     ClosureClassElement globalizedElement = new ClosureClassElement(
         node, closureName, compiler, element);
-    // Extend [globalizedElement] as an instantiated class in the closed world.
-    compiler.world.registerClass(
-        globalizedElement, isDirectlyInstantiated: true);
     FunctionElement callElement =
         new SynthesizedCallMethodElementX(Identifiers.call,
                                           element,