dart2js: Remove unused variable.

pkg/compiler/lib/src/js_emitter/old_emitter/container_builder.dart

 // Copyright (c) 2013, 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.
 
 part of dart2js.js_emitter;
 
 /// This class should morph into something that makes it easy to build
 /// JavaScript representations of libraries, class-sides, and instance-sides.
 /// Initially, it is just a placeholder for code that is moved from
 /// [CodeEmitterTask].
 class ContainerBuilder extends CodeEmitterHelper {
-  final Map<Element, Element> staticGetters = new Map<Element, Element>();
-
   bool needsSuperGetter(FunctionElement element) =>
     compiler.codegenWorld.methodsNeedingSuperGetter.contains(element);
 
   /**
    * Generate stubs to handle invocation of methods with optional
    * arguments.
    *
    * A method like [: foo([x]) :] may be invoked by the following
    * calls: [: foo(), foo(1), foo(x: 1) :]. See the sources of this
    * function for detailed examples.
@@ skipping 644 matching lines @@
     assert(needsStubs != null);
     assert(canTearOff != null);
     assert(isClosure != null);
     assert(tearOffName != null || !canTearOff);
     assert(canBeReflected != null);
     assert(canBeApplied != null);
     assert(hasSuperAlias != null);
     assert(needStructuredInfo != null);
   }
 }