Fix 56 hints in pkg/compiler

pkg/compiler/lib/src/tree/unparser.dart

 // Copyright (c) 2012, 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.
 
 part of tree;
 
 String unparse(Node node, {minify: true}) {
   Unparser unparser = new Unparser(minify: minify);
   unparser.unparse(node);
   return unparser.result;
@@ skipping 50 matching lines @@
   visitBlock(Block node) => unparseBlockStatements(node.statements);
 
   unparseBlockStatements(NodeList statements) {
     addToken(statements.beginToken);
 
     Link<Node> nodes = statements.nodes;
     if (nodes != null && !nodes.isEmpty) {
       indentMore();
       newline();
       visit(nodes.head);
-      String delimiter =
-        (statements.delimiter == null) ? "" : "${statements.delimiter}";
       for (Link link = nodes.tail; !link.isEmpty; link = link.tail) {
         newline();
         visit(link.head);
       }
       indentLess();
       newline();
     }
     if (statements.endToken != null) {
       write(statements.endToken.value);
     }
@@ skipping 769 matching lines @@
   }
 
   visitStatement(Statement node) {
     throw 'internal error'; // Should not be called.
   }
 
   visitStringNode(StringNode node) {
     throw 'internal error'; // Should not be called.
   }
 }