Fix for 'Extract Local' refactoring - take into account local variable elements.

pkg/analysis_server/test/services/refactoring/extract_local_test.dart

 // Copyright (c) 2014, 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 test.services.refactoring.extract_local;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_server/src/services/refactoring/extract_local.dart';
@@ skipping 578 matching lines @@
     return _assertSuccessfulRefactoring('''
 int foo() => 42;
 main() {
   var res = foo();
   int a = 1 + res;
   int b = 2 +  res; // marker
 }
 ''');
   }
 
+  test_occurences_differentVariable() {
+    indexTestUnit('''
+main() {
+  {
+    int v = 1;
+    print(v + 1); // marker
+    print(v + 1);
+  }
+  {
+    int v = 2;
+    print(v + 1);
+  }
+}
+''');
+    _createRefactoringWithSuffix('v + 1', '); // marker');
+    // apply refactoring
+    return _assertSuccessfulRefactoring('''
+main() {
+  {
+    int v = 1;
+    var res = v + 1;
+    print(res); // marker
+    print(res);
+  }
+  {
+    int v = 2;
+    print(v + 1);
+  }
+}
+''');
+  }
+
   test_occurences_useDominator() {
     indexTestUnit('''
 main() {
   if (true) {
     print(42);
   } else {
     print(42);
   }
 }
 ''');
@@ skipping 306 matching lines @@
     int length = search.length;
     _createRefactoring(offset, length);
   }
 
   void _createRefactoringWithSuffix(String selectionSearch, String suffix) {
     int offset = findOffset(selectionSearch + suffix);
     int length = selectionSearch.length;
     _createRefactoring(offset, length);
   }
 }