Add the missing space before 'in'.

pkg/analyzer/lib/src/dart/ast/utilities.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 analyzer.src.dart.ast.utilities;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_ast_factory.dart';
@@ skipping 2759 matching lines @@
   static void logException(AstNode node, AstVisitor visitor, dynamic exception,
       StackTrace stackTrace) {
     StringBuffer buffer = new StringBuffer();
     buffer.write('Exception while using a ${visitor.runtimeType} to visit a ');
     AstNode currentNode = node;
     bool first = true;
     while (currentNode != null) {
       if (first) {
         first = false;
       } else {
-        buffer.write('in ');
+        buffer.write(' in ');
       }
       buffer.write(currentNode.runtimeType);
       currentNode = currentNode.parent;
     }
     AnalysisEngine.instance.logger.logError(
         buffer.toString(), new CaughtException(exception, stackTrace));
   }
 }
 
 /**
@@ skipping 6590 matching lines @@
     if (node.star != null) {
       sink.write("yield* ");
     } else {
       sink.write("yield ");
     }
     safelyVisitNode(node.expression);
     sink.write(";");
     return null;
   }
 }