Rework Unparser/unparse StringBuffer management.

lib/compiler/implementation/tree/nodes.dart

Index: lib/compiler/implementation/tree/nodes.dart
diff --git a/lib/compiler/implementation/tree/nodes.dart b/lib/compiler/implementation/tree/nodes.dart
index c535d9a697bd9042dc5204530859e1056432fdc8..7fd2edc2f94d53524b1c36c5a86166b7582235ad 100644
--- a/lib/compiler/implementation/tree/nodes.dart
+++ b/lib/compiler/implementation/tree/nodes.dart
@@ -99,7 +99,7 @@ class Node implements Hashable {
   /**
    * Returns this node unparsed to Dart source string.
    */
-  toString() => unparse();
+  toString() => unparse(this);
 
   /**
    * Returns Xml-like tree representation of this node.
@@ -110,16 +110,6 @@ class Node implements Hashable {
 
   String getObjectDescription() => super.toString();
 
-  String unparse() {
-    Unparser unparser = new Unparser();
-    try {
-      return unparser.unparse(this);
-    } catch (e, trace) {
-      print(trace);
-      return '<<unparse error: ${getObjectDescription()}: ${unparser.sb}>>';
-    }
-  }
-
   abstract Token getBeginToken();
 
   abstract Token getEndToken();