Flatten inferrer implementation

pkg/compiler/lib/src/inferrer/list_tracer.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.
 
 library compiler.src.inferrer.list_tracer;
 
 import '../elements/elements.dart';
 import '../js_backend/backend_helpers.dart';
 import '../universe/selector.dart' show Selector;
 import '../util/util.dart' show Setlet;
@@ skipping 112 matching lines @@
   'lastIndexOf',
   'sublist',
   'getRange',
   'asMap',
 
   // From JSArray.
   'checkMutable',
   'checkGrowable',
 ]);
 
-class ListTracerVisitor extends TracerVisitor<ListTypeInformation> {
+class ListTracerVisitor extends TracerVisitor {
   // The [Set] of found assignments to the list.
   Set<TypeInformation> assignments = new Setlet<TypeInformation>();
   bool callsGrowableMethod = false;
 
   ListTracerVisitor(tracedType, inferrer) : super(tracedType, inferrer);
 
   /**
    * Returns [true] if the analysis completed successfully, [false] if it
    * bailed out. In the former case, [assignments] holds a list of
    * [TypeInformation] nodes that flow into the element type of this list.
@@ skipping 61 matching lines @@
         callsGrowableMethod = true;
         assignments.add(inferrer.types.nullType);
       }
     } else if (selector.isCall &&
         !info.targets.every((element) => element.isFunction)) {
       bailout('Passed to a closure');
       return;
     }
   }
 }