Refactor SourceFile, SourceFileProvider and SourceLocation.

tests/compiler/dart2js/warnings_checker.dart

 // Copyright (c) 2013, 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.
 
 // Test that dart2js produces the expected static type warnings to ensures that
 // the analyzer and dart2js agrees on the tests.
 
 import 'dart:async';
 import 'dart:io';
 import 'package:expect/expect.dart';
 import 'package:async_helper/async_helper.dart';
 import 'memory_compiler.dart';
 import 'package:compiler/src/filenames.dart';
 import 'package:compiler/src/io/source_file.dart';
 import 'package:compiler/src/source_file_provider.dart';
 import 'package:compiler/src/util/uri_extras.dart';
 import 'dart:convert';
 
 void checkWarnings(Map<String, dynamic> tests, [List<String> arguments]) {
   bool isWindows = Platform.isWindows;
   Uri script = currentDirectory.resolveUri(Platform.script);
   bool warningsMismatch = false;
   bool verbose = arguments != null && arguments.contains('-v');
   asyncTest(() => Future.forEach(tests.keys, (String test) {
     Uri uri = script.resolve('../../$test');
     String source = UTF8.decode(readAll(uriPathToNative(uri.path)));
     SourceFile file = new StringSourceFile(
-        relativize(currentDirectory, uri, isWindows), source);
+        uri, relativize(currentDirectory, uri, isWindows), source);
     Map<int,String> expectedWarnings = {};
     int lineNo = 0;
     for (String line in source.split('\n')) {
       if (line.contains('///') &&
           (line.contains('static type warning') ||
            line.contains('static warning'))) {
         expectedWarnings[lineNo] = line;
       }
       lineNo++;
     }
@@ skipping 35 matching lines @@
             print('$uri [${lineNo+1}]: Missing static type warning.');
             print(line);
           }
         }
       }
     });
   }).then((_) {
     Expect.isFalse(warningsMismatch);
   }));
 }