Fix hints reported by analyzer.

pkg/compiler/lib/src/resolution/resolution.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 dart2js.resolution;
 
 import 'dart:collection' show Queue;
 
 import '../common.dart';
 import '../common/names.dart' show Identifiers;
@@ skipping 29 matching lines @@
 import '../tokens/token.dart'
     show
         isBinaryOperator,
         isMinusOperator,
         isTernaryOperator,
         isUnaryOperator,
         isUserDefinableOperator;
 import '../tree/tree.dart';
 import '../universe/call_structure.dart' show CallStructure;
 import '../universe/feature.dart' show Feature;
-import '../universe/use.dart' show StaticUse, TypeUse;
+import '../universe/use.dart' show StaticUse;
 import '../universe/world_impact.dart' show WorldImpact;
 import '../util/util.dart' show Link, Setlet;
 import '../world.dart';
 import 'class_hierarchy.dart';
 import 'class_members.dart' show MembersCreator;
 import 'constructors.dart';
 import 'members.dart';
 import 'registry.dart';
 import 'resolution_result.dart';
 import 'signatures.dart';
@@ skipping 448 matching lines @@
     // [target] is now the actual target of the redirections.  Run through
     // the constructors again and set their [redirectionTarget], so that we
     // do not have to run the loop for these constructors again. Furthermore,
     // compute [redirectionTargetType] for each factory by computing the
     // substitution of the target type with respect to the factory type.
     while (!seen.isEmpty) {
       ConstructorElementX factory = seen.removeLast();
       ResolvedAst resolvedAst = factory.resolvedAst;
       assert(invariant(node, resolvedAst != null,
           message: 'No ResolvedAst for $factory.'));
-      FunctionExpression functionNode = resolvedAst.node;
       RedirectingFactoryBody redirectionNode = resolvedAst.body;
       ResolutionDartType factoryType =
           resolvedAst.elements.getType(redirectionNode);
       if (!factoryType.isDynamic) {
         targetType = targetType.substByContext(factoryType);
       }
       factory.setEffectiveTarget(target, targetType, isMalformed: isMalformed);
     }
   }
 
@@ skipping 608 matching lines @@
   TreeElements get treeElements {
     assert(invariant(this, _treeElements != null,
         message: "TreeElements have not been computed for $this."));
     return _treeElements;
   }
 
   void reuseElement() {
     _treeElements = null;
   }
 }