anchor.diff:  
     _translateCatchClauses(List<ast.CatchClause> clauses, rk, ek, sk) {
       var savedExceptionName = currentExceptionName;
  +    var savedStackTraceName = currentStackTraceName;
       var catchName = newName('catch');
       var exceptionName, stackTraceName, catchBlock;
       if (clauses.isEmpty) {
         exceptionName = currentExceptionName = newName('e');
  -      stackTraceName = newName('s');
  +      stackTraceName = currentStackTraceName = newName('s');
         catchBlock = make.block([ek.apply(exceptionName, stackTraceName)]);
       } else {
         // The exception and stack trace parameters do not necessarily have the
  
positive.code:                make.block([ek.apply(exceptionName, stackTraceName)]))]);
      }
      currentExceptionName = savedExceptionName;
      addStatement(make.functionDeclarationStatement(catchName,
          [exceptionName, stackTraceName], catchBlock));
      return catchName;
  
negative.code:     breakTargets = <JumpTarget>[];
      continueTargets = <JumpTarget>[];
      currentExceptionName = null;
      currentStackTraceName = null;
      awaits = analysis.awaits;
      labels = analysis.labels;
      names = analysis.names;
  