Remove scanBuiltinLibraries.

sdk/lib/_internal/compiler/implementation/dart_backend/backend.dart

 // Copyright (c) 2012, 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.
 
 part of dart_backend;
 
 // TODO(ahe): This class is simply wrong.  This backend should use
 // elements when it can, not AST nodes.  Perhaps a [Map<Element,
 // TreeElements>] is what is needed.
 class ElementAst {
@@ skipping 443 matching lines @@
         nonPlatformSize += compilationUnit.script.file.length;
       }
     }
     int percentage = compiler.assembledCode.length * 100 ~/ nonPlatformSize;
     log('Total used non-platform files size: ${nonPlatformSize} bytes, '
         'bundle size: ${compiler.assembledCode.length} bytes (${percentage}%)');
   }
 
   log(String message) => compiler.log('[DartBackend] $message');
 
-  Future onLibraryLoaded(LibraryElement library, Uri uri) {
-    if (useMirrorHelperLibrary && library == compiler.mirrorsLibrary) {
-      return compiler.scanBuiltinLibrary(
-          MirrorRenamer.MIRROR_HELPER_LIBRARY_NAME).
+  Future onLibrariesLoaded(Map<Uri, LibraryElement> loadedLibraries) {
+    if (useMirrorHelperLibrary &&
+        loadedLibraries.containsKey(Compiler.DART_MIRRORS)) {
+      return compiler.libraryLoader.loadLibrary(
+          compiler.translateResolvedUri(
+              loadedLibraries[Compiler.DART_MIRRORS],
+              MirrorRenamer.DART_MIRROR_HELPER, null)).
           then((LibraryElement element) {
         mirrorHelperLibrary = element;
         mirrorHelperGetNameFunction = mirrorHelperLibrary.find(
             MirrorRenamer.MIRROR_HELPER_GET_NAME_FUNCTION);
         mirrorHelperSymbolsMap = mirrorHelperLibrary.find(
             MirrorRenamer.MIRROR_HELPER_SYMBOLS_MAP_NAME);
       });
     }
     return new Future.value();
   }
@@ skipping 156 matching lines @@
   }
 
   Constant compileMetadata(MetadataAnnotation metadata,
                            Node node,
                            TreeElements elements) {
     return measure(() {
       return constantCompiler.compileMetadata(metadata, node, elements);
     });
   }
 }