Integration of MOVE_FILE into the server and a couple of fixes.

pkg/analysis_server/lib/src/services/refactoring/move_file.dart

 // Copyright (c) 2014, 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 services.src.refactoring.move_file;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart' hide Element;
 import 'package:analysis_server/src/services/correction/status.dart';
@@ skipping 80 matching lines @@
       return change;
     });
   }
 
   @override
   bool requiresPreview() => false;
 
   void _updateUriReference(UriReferencedElement element) {
     if (!element.isSynthetic) {
       String elementUri = element.uri;
-      if (pathos.isRelative(elementUri)) {
+      if (_isRelativeUri(elementUri)) {
         String elementPath = pathos.join(oldLibraryDir, elementUri);
         String newUri = pathos.relative(elementPath, from: newLibraryDir);
         int uriOffset = element.uriOffset;
         int uriLength = element.uriEnd - uriOffset;
         change.addElementEdit(
             library,
             new SourceEdit(uriOffset, uriLength, "'$newUri'"));
       }
     }
   }
 
   void _updateUriReferences(List<UriReferencedElement> elements) {
     for (UriReferencedElement element in elements) {
       _updateUriReference(element);
     }
   }
+
+  /**
+   * Checks if the given [path] represents a relative URI.
+   *
+   * The following URI's are not relative:
+   *    `/absolute/path/file.dart`
+   *    `dart:math`
+   */
+  static bool _isRelativeUri(String path) {
+    // absolute path
+    if (pathos.isAbsolute(path)) {
+      return false;
+    }
+    // absolute URI
+    if (Uri.parse(path).isAbsolute) {
+      return false;
+    }
+    // OK
+    return true;
+  }
 }