Convert resource providers to use FileSource

pkg/analyzer/lib/src/source/source_resource.dart

 // Copyright (c) 2016, 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.source.source_resource;
 
 import 'dart:collection';
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/generated/engine.dart';
@@ skipping 66 matching lines @@
    *
    * Clients should consider using the method [AnalysisContext.getContents]
    * because contexts can have local overrides of the content of a source that
    * the source is not aware of.
    *
    * Throws an exception if the contents of this source could not be accessed.
    * See [contents].
    */
   TimestampedData<String> get contentsFromFile {
     return new TimestampedData<String>(
-        file.modificationStamp, fileReadMode(file.readAsStringSync()));
+        modificationStamp, fileReadMode(file.readAsStringSync()));
   }
 
   @override
   String get encoding => _encoding ??= uri.toString();
 
   @override
   String get fullName => _absolutePath ??= file.path;
 
   @override
-  int get hashCode => id;
+  int get hashCode => uri.hashCode;
 
   @override
   bool get isInSystemLibrary => uri.scheme == DartUriResolver.DART_SCHEME;
 
   @override
-  int get modificationStamp => file.modificationStamp;
+  int get modificationStamp {
+    try {
+      return file.modificationStamp;
+    } on FileSystemException {
+      return -1;
+    }
+  }
 
   @override
   String get shortName => file.shortName;
 
   @override
   UriKind get uriKind => UriKind.fromScheme(uri.scheme);
 
   @override
   bool operator ==(Object object) {
     if (object is FileSource) {
       return id == object.id;
     } else if (object is Source) {
       return uri == object.uri;
     }
     return false;
   }
 
   @override
   bool exists() => file.exists;
 
   @override
   String toString() {
     if (file == null) {
       return "<unknown source>";
     }
     return file.path;
   }
 }