First prototype of import map generator.

utils/import_mapper/passthrough_hook.dart

Index: utils/import_mapper/passthrough_hook.dart
diff --git a/utils/import_mapper/passthrough_hook.dart b/utils/import_mapper/passthrough_hook.dart
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+// 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.
+
+/**
+ * A trivial identity import hook that generates an import map that maps all
+ * imports to their original import string.
+ */
+#library('passthrough_hook');
+
+#import('import_mapper.dart');
+
+void main() {
+  printImportMap((context, name) => name);
+}