Remove code supporting incremental compilation in dart2js

pkg/compiler/lib/src/closure.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library closureToClassMapper;
 
 import 'common/names.dart' show Identifiers;
 import 'common/resolution.dart' show ParsingContext, Resolution;
 import 'common/tasks.dart' show CompilerTask;
 import 'common.dart';
@@ skipping 97 matching lines @@
             _closureMappingCache[element] =
                 new ClosureClassMap(null, null, null, new ThisLocal(element));
           }
         }
         assert(invariant(element, _closureMappingCache[element] != null,
             message: "No ClosureClassMap computed for ${element}."));
         return _closureMappingCache[element];
       });
     });
   }
-
-  void forgetElement(var closure) {
-    ClosureClassElement cls;
-    if (closure is ClosureFieldElement) {
-      cls = closure.closureClass;
-    } else if (closure is SynthesizedCallMethodElementX) {
-      cls = closure.closureClass;
-    } else {
-      throw new SpannableAssertionFailure(
-          closure, 'Not a closure: $closure (${closure.runtimeType}).');
-    }
-    compiler.enqueuer.codegen.forgetEntity(cls, compiler);
-  }
 }
 
 /// Common interface for [BoxFieldElement] and [ClosureFieldElement] as
 /// non-elements.
 // TODO(johnniwinther): Remove `implements Element`.
 abstract class CapturedVariable implements Element {}
 
 // TODO(ahe): These classes continuously cause problems.  We need to
 // find a more general solution.
 class ClosureFieldElement extends ElementX
@@ skipping 1084 matching lines @@
 ///
 /// Move the below classes to a JS model eventually.
 ///
 abstract class JSEntity implements Entity {
   Entity get declaredEntity;
 }
 
 abstract class PrivatelyNamedJSEntity implements JSEntity {
   Entity get rootOfScope;
 }