Refactor SourceFile, SourceFileProvider and SourceLocation.

pkg/dart2js_incremental/lib/library_updater.dart

Index: pkg/dart2js_incremental/lib/library_updater.dart
diff --git a/pkg/dart2js_incremental/lib/library_updater.dart b/pkg/dart2js_incremental/lib/library_updater.dart
index bc269e2d7cea25f2842ad8d79d43c7e86bf2cde8..003740cc94cca77f6e1855ed3f445e04766fe4f7 100644
--- a/pkg/dart2js_incremental/lib/library_updater.dart
+++ b/pkg/dart2js_incremental/lib/library_updater.dart
@@ -290,10 +290,11 @@ class LibraryUpdater extends JsFeatures {
     }
 
     return _readUri(before.resourceUri).then((bytes) {
+      Uri uri = before.file.uri;
       String filename = before.file.filename;
       SourceFile sourceFile = bytes is String
-          ? new StringSourceFile(filename, bytes)
-          : new CachingUtf8BytesSourceFile(filename, bytes);
+          ? new StringSourceFile(uri, filename, bytes)
+          : new CachingUtf8BytesSourceFile(uri, filename, bytes);
       return before.copyWithFile(sourceFile);
     });
   }