Make rebaselining not use gigabytes of memory.

Tools/Scripts/webkitpy/layout_tests/models/test_expectations.py

 # Copyright (C) 2010 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 1008 matching lines @@
 
     def _process_tests_without_expectations(self):
         if self._full_test_list:
             for test in self._full_test_list:
                 if not self._model.has_test(test):
                     self._model.add_expectation_line(TestExpectationLine.create_passing_expectation(test))
 
     def has_warnings(self):
         return self._has_warnings
 
-    def remove_configuration_from_test(self, test, test_configuration):
+    def remove_configurations(self, removals):
         expectations_to_remove = []
         modified_expectations = []
 
-        for expectation in self._expectations:
-            if expectation.name != test or not expectation.parsed_expectations:
-                continue
-            if test_configuration not in expectation.matching_configurations:
-                continue
+        for test, test_configuration in removals:
+            for expectation in self._expectations:
+                if expectation.name != test or not expectation.parsed_expectations:
+                    continue
+                if test_configuration not in expectation.matching_configurations:
+                    continue
 
-            expectation.matching_configurations.remove(test_configuration)
-            if expectation.matching_configurations:
-                modified_expectations.append(expectation)
-            else:
-                expectations_to_remove.append(expectation)
+                expectation.matching_configurations.remove(test_configuration)
+                if expectation.matching_configurations:
+                    modified_expectations.append(expectation)
+                else:
+                    expectations_to_remove.append(expectation)
 
         for expectation in expectations_to_remove:
             index = self._expectations.index(expectation)
             self._expectations.remove(expectation)
 
             if index == len(self._expectations) or self._expectations[index].is_whitespace_or_comment():
                 while index and self._expectations[index - 1].is_whitespace_or_comment():
                     index = index - 1
                     self._expectations.pop(index)
 
@@ skipping 49 matching lines @@
             # If reconstitute_only_these is an empty list, we want to return original_string.
             # So we need to compare reconstitute_only_these to None, not just check if it's falsey.
             if reconstitute_only_these is None or expectation_line in reconstitute_only_these:
                 return expectation_line.to_string(test_configuration_converter)
             return expectation_line.original_string
 
         def nones_out(expectation_line):
             return expectation_line is not None
 
         return "\n".join(filter(nones_out, map(serialize, expectation_lines)))