Roll Observatory packages and add a roll script

source_span/lib/src/utils.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 source_span.utils;
-
-/// Returns the minimum of [obj1] and [obj2] according to
-/// [Comparable.compareTo].
-Comparable min(Comparable obj1, Comparable obj2) =>
-    obj1.compareTo(obj2) > 0 ? obj2 : obj1;
-
-/// Returns the maximum of [obj1] and [obj2] according to
-/// [Comparable.compareTo].
-Comparable max(Comparable obj1, Comparable obj2) =>
-    obj1.compareTo(obj2) > 0 ? obj1 : obj2;
-
-/// Finds a line in [context] containing [text] at the specified [column].
-///
-/// Returns the index in [context] where that line begins, or null if none
-/// exists.
-int findLineStart(String context, String text, int column) {
-  var isEmpty = text == '';
-  var index = context.indexOf(text);
-  while (index != -1) {
-    var lineStart = context.lastIndexOf('\n', index) + 1;
-    var textColumn = index - lineStart;
-    if (column == textColumn || (isEmpty && column == textColumn + 1)) {
-      return lineStart;
-    }
-    index = context.indexOf(text, index + 1);
-  }
-  return null;
-}