Revert "Package map source factory support" [TBR].

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 f13fc8530161e979e207a0d37e487936c41e3664..1c60f5d19a5778b6f3ee59254b09ff2a8b0802d7 100644
--- a/pkg/analyzer/lib/src/generated/source_io.dart
+++ b/pkg/analyzer/lib/src/generated/source_io.dart
@@ -283,13 +283,6 @@ 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.file.getAbsolutePath());
-    }
-    return null;
-  }
   /**
    * Return `true` if the given URI is a `file` URI.
    *