Roll Observatory packages and add a roll script

charted/lib/core/utils.dart

-//
-// Copyright 2014 Google Inc. All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file or at
-// https://developers.google.com/open-source/licenses/bsd
-//
-
-/// A collection of utilities for use by rest of the library and it's users
-library charted.core.utils;
-
-import "dart:html" show Element, NodeTreeSanitizer;
-import "dart:math" as math;
-import "dart:async";
-
-import "package:intl/intl.dart" show BidiFormatter, Bidi, TextDirection;
-import "package:collection/collection.dart";
-import "package:quiver/core.dart";
-
-part 'utils/color.dart';
-part 'utils/disposer.dart';
-part 'utils/lists.dart';
-part 'utils/math.dart';
-part 'utils/namespace.dart';
-part 'utils/object_factory.dart';
-part 'utils/rect.dart';
-part 'utils/bidi_formatter.dart';
-
-const String ORIENTATION_LEFT   = 'left';
-const String ORIENTATION_RIGHT  = 'right';
-const String ORIENTATION_TOP    = 'top';
-const String ORIENTATION_BOTTOM = 'bottom';
-
-/// Identity function that returns the value passed as it's parameter.
-identityFunction(x) => x;
-
-/// Function that formats a value to String.
-typedef String FormatFunction(value);
-
-/// Test if the given String or Iterable, [val] is null or empty
-bool isNullOrEmpty(val) {
-  assert(val == null || val is String || val is Iterable);
-  return val == null || val.isEmpty;
-}
-
-/// An empty tree sanitizer for use with Element.html
-/// This sanitizer must not be used when attaching user input to the DOM.
-class NullTreeSanitizer implements NodeTreeSanitizer {
-  void sanitizeTree(_) {}
-}