Remove unnecessary casts and general code clean-up

pkg/analyzer/lib/src/dart/resolver/scope.dart

 // Copyright (c) 2014, 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 analyzer.src.dart.resolver.scope;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
@@ skipping 372 matching lines @@
       Element element = nameSpace.get(name);
       if (element != null) {
         if (foundElement == null) {
           foundElement = element;
         } else if (!identical(foundElement, element)) {
           foundElement = MultiplyDefinedElementImpl.fromElements(
               _definingLibrary.context, foundElement, element);
         }
       }
     }
-    if (foundElement is MultiplyDefinedElementImpl) {
-      foundElement = _removeSdkElements(
-          identifier, name, foundElement as MultiplyDefinedElementImpl);
+    Element element = foundElement;
+    if (element is MultiplyDefinedElementImpl) {
+      foundElement = _removeSdkElements(identifier, name, element);
     }
     if (foundElement is MultiplyDefinedElementImpl) {
       String foundEltName = foundElement.displayName;
       List<Element> conflictingMembers = foundElement.conflictingElements;
       int count = conflictingMembers.length;
       List<String> libraryNames = new List<String>(count);
       for (int i = 0; i < count; i++) {
         libraryNames[i] = _getLibraryName(conflictingMembers[i]);
       }
       libraryNames.sort();
@@ skipping 644 matching lines @@
 
   /**
    * Define the type parameters declared by the [classElement].
    */
   void _defineTypeParameters(ClassElement classElement) {
     for (TypeParameterElement typeParameter in classElement.typeParameters) {
       define(typeParameter);
     }
   }
 }