Handle migration status entries into split up status files.

tools/migration/bin/migrate_batch.dart

 // Copyright (c) 2017, 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.
 
 /// Given the beginning and ending file names in a batch, does as much automated
 /// migration and possible and prints out the remaining manual steps required.
 ///
 /// This should be safe to run, and safe to re-run on an in-progress chunk.
 /// However, it has not been thoroughly tested, so run at your own risk.
 
@@ skipping 49 matching lines @@
   for (var test in tests) {
     var todos = test.migrate();
     if (todos.isEmpty) {
       migratedTests++;
     } else {
       unmigratedTests++;
       allTodos[test.twoPath] = todos;
     }
   }
 
-  migrateStatusEntries(tests);
+  migrateStatusEntries(tests, allTodos);
 
   // Tell the user what's left to do.
   print("");
   var summary = "";
 
   if (migratedTests > 0) {
     var s = migratedTests == 1 ? "" : "s";
     summary += "Successfully migrated ${green(migratedTests)} test$s. ";
   }
 
   if (unmigratedTests > 0) {
     var s = unmigratedTests == 1 ? "" : "s";
     summary += "Need manual work on ${red(unmigratedTests)} test$s:";
   }
 
   print(summary);
   var todoTests = allTodos.keys.toList();
   todoTests.sort();
   for (var todoTest in todoTests) {
     print("- ${bold(todoTest)}:");
     allTodos[todoTest].forEach(todo);
   }
 }