Remove unnecessary casts and general code clean-up

pkg/analyzer/lib/src/generated/error.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.generated.error;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart' show AstNode;
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 3249 matching lines @@
           return buffer.toString();
         }
       }
       return type.displayName;
     }
     if (_hasEqualTypeNames(arguments)) {
       int count = arguments.length;
       for (int i = 0; i < count; i++) {
         Object argument = arguments[i];
         if (argument is DartType) {
-          DartType type = argument;
-          Element element = type.element;
+          Element element = argument.element;
           if (element == null) {
-            arguments[i] = displayName(type);
+            arguments[i] = displayName(argument);
           } else {
-            arguments[i] = element.getExtendedDisplayName(displayName(type));
+            arguments[i] =
+                element.getExtendedDisplayName(displayName(argument));
           }
         }
       }
     } else {
       int count = arguments.length;
       for (int i = 0; i < count; i++) {
         Object argument = arguments[i];
         if (argument is DartType) {
           arguments[i] = displayName(argument);
         }
       }
     }
   }
 
   /**
    * Return `true` if the given array of [arguments] contains two or more types
    * with the same display name.
    */
   bool _hasEqualTypeNames(List<Object> arguments) {
     int count = arguments.length;
     HashSet<String> typeNames = new HashSet<String>();
     for (int i = 0; i < count; i++) {
-      if (arguments[i] is DartType &&
-          !typeNames.add((arguments[i] as DartType).displayName)) {
+      Object argument = arguments[i];
+      if (argument is DartType && !typeNames.add(argument.displayName)) {
         return true;
       }
     }
     return false;
   }
 }
 
 /**
  * The severity of an [ErrorCode].
  */
@@ skipping 270 matching lines @@
   /**
    * Generate a hint for a constructor, function or method invocation where a
    * required parameter is missing.
    *
    * Parameters:
    * 0: the name of the parameter
    */
   static const HintCode MISSING_REQUIRED_PARAM = const HintCode(
       'MISSING_REQUIRED_PARAM', "The parameter '{0}' is required.");
 
-
   /**
    * Generate a hint for a constructor, function or method invocation where a
    * required parameter is missing.
    *
    * Parameters:
    * 0: the name of the parameter
    * 1: message details
    */
   static const HintCode MISSING_REQUIRED_PARAM_WITH_DETAILS = const HintCode(
       'MISSING_REQUIRED_PARAM', "The parameter '{0}' is required. {1}");
@@ skipping 2210 matching lines @@
    * Initialize a newly created error code to have the given [name].
    */
   const TodoCode(String name) : super(name, "{0}");
 
   @override
   ErrorSeverity get errorSeverity => ErrorSeverity.INFO;
 
   @override
   ErrorType get type => ErrorType.TODO;
 }