pkg/csslib: remove unused vars and fields

lib/src/tree_printer.dart

 // Copyright (c) 2013, 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 csslib.visitor;
 
 // TODO(terry): Enable class for debug only; when conditional imports enabled.
 
 /** Helper function to dump the CSS AST. */
 String treeToDebugString(StyleSheet styleSheet, [bool useSpan = false]) {
@@ skipping 372 matching lines @@
   }
 
   void visitNumberTerm(NumberTerm node) {
     heading('NumberTerm', node);
     output.depth++;
     output.writeValue('value', node.text);
     output.depth--;
   }
 
   void visitUnitTerm(UnitTerm node) {
-    String unitValue;
-
     output.depth++;
     output.writeValue('value', node.text);
     output.writeValue('unit', node.unitToString());
     output.depth--;
   }
 
   void visitLengthTerm(LengthTerm node) {
     heading('LengthTerm', node);
     super.visitLengthTerm(node);
   }
@@ skipping 146 matching lines @@
   }
 
   void visitPaddingExpression(PaddingExpression node) {
     heading('Dart Style PaddingExpression', node);
   }
 
   void visitWidthExpression(WidthExpression node) {
     heading('Dart Style WidthExpression', node);
   }
 }