Rollback 6bee780067d3c84bfbc387720a26b0eabe7c2357, restore PrintWriter.

pkg/analyzer/lib/src/dart/ast/ast.dart

Index: pkg/analyzer/lib/src/dart/ast/ast.dart
diff --git a/pkg/analyzer/lib/src/dart/ast/ast.dart b/pkg/analyzer/lib/src/dart/ast/ast.dart
index d5ed4cf2b77d3f55d092b18a535e986a77d78a75..0b23ed06fb4a2dfca5dd55972fd6292517790a60 100644
--- a/pkg/analyzer/lib/src/dart/ast/ast.dart
+++ b/pkg/analyzer/lib/src/dart/ast/ast.dart
@@ -16,6 +16,7 @@ import 'package:analyzer/src/dart/ast/utilities.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/generated/engine.dart' show AnalysisEngine;
+import 'package:analyzer/src/generated/java_core.dart';
 import 'package:analyzer/src/generated/java_engine.dart';
 import 'package:analyzer/src/generated/parser.dart';
 import 'package:analyzer/src/generated/source.dart' show LineInfo, Source;
@@ -938,9 +939,9 @@ abstract class AstNodeImpl implements AstNode {
 
   @override
   String toSource() {
-    StringBuffer buffer = new StringBuffer();
-    accept(new ToSourceVisitor(buffer));
-    return buffer.toString();
+    PrintStringWriter writer = new PrintStringWriter();
+    accept(new ToSourceVisitor(writer));
+    return writer.toString();
   }
 
   @override