dart2js: Fix hints in code base.

pkg/compiler/lib/src/resolution/class_hierarchy.dart

 // Copyright (c) 2015, 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 resolution;
 
 class TypeDefinitionVisitor extends MappingVisitor<DartType> {
   Scope scope;
   final TypeDeclarationElement enclosingElement;
   TypeDeclarationElement get element => enclosingElement;
@@ skipping 84 matching lines @@
 
   DartType visitClassNode(ClassNode node) {
     if (element == null) {
       throw compiler.internalError(node, 'element is null');
     }
     if (element.resolutionState != STATE_STARTED) {
       throw compiler.internalError(element,
           'cyclic resolution of class $element');
     }
 
-    InterfaceType type = element.computeType(compiler);
+    element.computeType(compiler);
     scope = new TypeDeclarationScope(scope, element);
     // TODO(ahe): It is not safe to call resolveTypeVariableBounds yet.
     // As a side-effect, this may get us back here trying to
     // resolve this class again.
     resolveTypeVariableBounds(node.typeParameters);
 
     // Setup the supertype for the element (if there is a cycle in the
     // class hierarchy, it has already been set to Object).
     if (element.supertype == null && node.superclass != null) {
       MixinApplication superMixin = node.superclass.asMixinApplication();
@@ skipping 120 matching lines @@
           'cyclic resolution of class $element');
     }
 
     if (identical(node.classKeyword.stringValue, 'typedef')) {
       // TODO(aprelev@gmail.com): Remove this deprecation diagnostic
       // together with corresponding TODO in parser.dart.
       compiler.reportWarning(node.classKeyword,
           MessageKind.DEPRECATED_TYPEDEF_MIXIN_SYNTAX);
     }
 
-    InterfaceType type = element.computeType(compiler);
+    element.computeType(compiler);
     scope = new TypeDeclarationScope(scope, element);
     resolveTypeVariableBounds(node.typeParameters);
 
     // Generate anonymous mixin application elements for the
     // intermediate mixin applications (excluding the last).
     DartType supertype = resolveSupertype(element, node.superclass);
     Link<Node> link = node.mixins.nodes;
     while (!link.tail.isEmpty) {
       supertype = applyMixin(supertype, checkMixinType(link.head), link.head);
       link = link.tail;
@@ skipping 372 matching lines @@
     Identifier selector = node.selector.asIdentifier();
     var e = prefixElement.lookupLocalMember(selector.source);
     if (e == null || !e.impliesType) {
       error(node.selector, MessageKind.CANNOT_RESOLVE_TYPE,
             {'typeName': node.selector});
       return;
     }
     loadSupertype(e, node);
   }
 }