Fix exception handling

pkg/analyzer/lib/src/generated/engine.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.
 
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine;
 
 import "dart:math" as math;
@@ skipping 6820 matching lines @@
   /**
    * Perform this analysis task, ensuring that all exceptions are wrapped in an
    * [AnalysisException].
    *
    * @throws AnalysisException if any exception occurs while performing the task
    */
   void _safelyPerform() {
     try {
       internalPerform();
     } on AnalysisException catch (exception) {
-      throw exception;
+      rethrow;
     } catch (exception, stackTrace) {
       throw new AnalysisException(
           exception.toString(),
           new CaughtException(exception, stackTrace));
     }
   }
 }
 
 /**
  * An `AnalysisTaskVisitor` visits tasks. While tasks are not structured in any
@@ skipping 5577 matching lines @@
     if (element.id == _id) {
       result = element;
       throw new _ElementByIdFinderException();
     }
     super.visitElement(element);
   }
 }
 
 class _ElementByIdFinderException {
 }