Package map source factory support [FIXED].

pkg/analyzer/lib/src/generated/source_io.dart

Index: pkg/analyzer/lib/src/generated/source_io.dart
diff --git a/pkg/analyzer/lib/src/generated/source_io.dart b/pkg/analyzer/lib/src/generated/source_io.dart
index 1c60f5d19a5778b6f3ee59254b09ff2a8b0802d7..9c40d7461b4666ffb553a8b69545968bc2b0ee28 100644
--- a/pkg/analyzer/lib/src/generated/source_io.dart
+++ b/pkg/analyzer/lib/src/generated/source_io.dart
@@ -283,6 +283,14 @@ class FileUriResolver extends UriResolver {
     return new FileBasedSource(new JavaFile.fromUri(uri), uri);
   }
 
+  @override
+  Uri restoreAbsolute(Source source) {
+    if (source is FileBasedSource) {
+      return new Uri.file(source.fullName);
+    }
+    return null;
+  }
+  
   /**
    * Return `true` if the given URI is a `file` URI.
    *