Consolidate duplicate code for resloving URIs.

pkg/analyzer/test/generated/test_support.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.test.generated.test_support;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart' show AstNode, SimpleIdentifier;
 import 'package:analyzer/dart/element/element.dart';
@@ skipping 606 matching lines @@
 
   bool exists() => exists2;
   void getContentsToReceiver(Source_ContentReceiver receiver) {
     throw new UnsupportedOperationException();
   }
 
   Source resolve(String uri) {
     throw new UnsupportedOperationException();
   }
 
-  Uri resolveRelativeUri(Uri uri) {
-    return new Uri(scheme: 'file', path: _name).resolveUri(uri);
-  }
-
   void setContents(String value) {
     generateExceptionOnRead = false;
     _modificationStamp = new DateTime.now().millisecondsSinceEpoch;
     _contents = value;
   }
 
   @override
   String toString() => '$_name';
 }
 
@@ skipping 15 matching lines @@
     }
     return UriKind.FILE_URI;
   }
 
   bool operator ==(Object other) {
     if (other is TestSource) {
       return other.uri == uri;
     }
     return false;
   }
-
-  Uri resolveRelativeUri(Uri uri) {
-    return this.uri.resolveUri(uri);
-  }
 }