Fix static warnings in test_suite.dart from local variables shadowing parameters or functions.

client/tests/dartc/test_config.dart

 // Copyright (c) 2011, 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.
 
 #library("client_dartc_test_config");
 
 #import("../../../tools/testing/dart/test_suite.dart");
 
 class ClientDartcTestSuite extends DartcCompilationTestSuite {
   ClientDartcTestSuite(Map configuration)
@@ skipping 11 matching lines @@
                'testing',
                'tests',
                'touch',
                'util',
                'view',
                'weld'],
               ["client/tests/dartc/dartc.status"]);
 
   bool isTestFile(String filename) {
     if (!filename.endsWith(".dart")) return false;
-    var options = optionsFromFile(filename);
-    return optionsFromFile(filename)["containsLeadingHash"];
+    // Using readOptionsFromFile here causes the file to be read twice,
+    // because readOptionsFromFile is called again in the superclass.
+    // Avoid this in new code.
+    return readOptionsFromFile(filename)["containsLeadingHash"];
   }
 
   bool listRecursively() => true;
 }