Roll Observatory deps (charted -> ^0.3.0)

packages/charted/lib/core/interpolators.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 interpolator generators and easing functions.
-/// 
+///
 /// Interpolators provide intermediate state when transitioning from one
 /// frame to another in an animation.
-/// 
-/// Easing functions indicate progress of an animation to interpolators. 
-/// 
+///
+/// Easing functions indicate progress of an animation to interpolators.
+///
 /// Currently provides interpolator for various types, including basic types
 /// like numbers, colors, strings, transforms and for iterables.
 library charted.core.interpolators;
 
 import 'dart:math' as math;
 import 'package:charted/core/utils.dart';
 
 part 'interpolators/interpolators.dart';
 part 'interpolators/easing.dart';