Use source_span rather than source_maps in csslib.

pkg/csslib/lib/src/messages.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.
 
 library csslib.src.messages;
 
 import 'package:logging/logging.dart' show Level;
-import 'package:source_maps/span.dart' show Span;
+import 'package:source_span/source_span.dart';
 
 import 'options.dart';
 
 // TODO(terry): Remove the global messages, use some object that tracks
 //              compilation state.
 
 /** The global [Messages] for tracking info/warnings/messages. */
 Messages messages;
 
 // Color constants used for generating messages.
@@ skipping 17 matching lines @@
   labels[Level.SEVERE] = 'error';
   labels[Level.WARNING] = 'warning';
   labels[Level.INFO] = 'info';
   return labels;
 })();
 
 /** A single message from the compiler. */
 class Message {
   final Level level;
   final String message;
-  final Span span;
+  final SourceSpan span;
   final bool useColors;
 
-  Message(this.level, this.message, {Span span, bool useColors: false})
+  Message(this.level, this.message, {SourceSpan span, bool useColors: false})
       : this.span = span, this.useColors = useColors;
 
   String toString() {
     var output = new StringBuffer();
     bool colors = useColors && _ERROR_COLORS.containsKey(level);
-    var levelColor =  _ERROR_COLORS[level];
+    var levelColor = colors ? _ERROR_COLORS[level] : null;
     if (colors) output.write(levelColor);
     output..write(_ERROR_LABEL[level])..write(' ');
     if (colors) output.write(NO_COLOR);
 
     if (span == null) {
       output.write(message);
     } else {
       output.write('on ');
-      output.write(span.getLocationMessage(message, useColors: colors,
-          color: levelColor));
+      output.write(span.message(message, color: levelColor));
     }
 
     return output.toString();
   }
 }
 
 typedef void PrintHandler(Message obj);
 
 /**
  * This class tracks and prints information, warnings, and errors emitted by the
  * compiler.
  */
 class Messages {
   /** Called on every error. Set to blank function to supress printing. */
   final PrintHandler printHandler;
 
   final PreprocessorOptions options;
 
   final List<Message> messages = <Message>[];
 
   Messages({PreprocessorOptions options, this.printHandler: print})
       : options = options != null ? options : new PreprocessorOptions();
 
   /** Report a compile-time CSS error. */
-  void error(String message, Span span) {
+  void error(String message, SourceSpan span) {
     var msg = new Message(Level.SEVERE, message, span: span,
         useColors: options.useColors);
 
     messages.add(msg);
 
     printHandler(msg);
   }
 
   /** Report a compile-time CSS warning. */
-  void warning(String message, Span span) {
+  void warning(String message, SourceSpan span) {
     if (options.warningsAsErrors) {
       error(message, span);
     } else {
       var msg = new Message(Level.WARNING, message, span: span,
           useColors: options.useColors);
 
       messages.add(msg);
     }
   }
 
   /** Report and informational message about what the compiler is doing. */
-  void info(String message, Span span) {
+  void info(String message, SourceSpan span) {
     var msg = new Message(Level.INFO, message, span: span,
         useColors: options.useColors);
 
     messages.add(msg);
 
     if (options.verbose) printHandler(msg);
   }
 
   /** Merge [newMessages] to this message lsit. */
   void mergeMessages(Messages newMessages) {
     messages.addAll(newMessages.messages);
     newMessages.messages.where((message) =>
         message.level.value == Level.SEVERE || options.verbose)
         .forEach((message) { printHandler(message); });
   }
 }