[Specs] Remove all the obsolete specs.

sky/specs/animation.md

-Animation API
-=============
-
-```dart
-typedef void TimerCallback();
-
-external void _addTask({ TimerCallback callback, Duration budget, int bits, int priority, Queue queue });
-// see (runloop.md)[runloop.md] for the semantics of tasks and queues
-// _addTask() does the zone magic on callback
-
-external final Queue get _idleQueue;
-external final Queue get _paintQueue;
-external final Queue get _nextPaintQueue;
-
-class AnimationTimer extends Timer {
-  factory whenIdle(TimerCallback callback, { Duration budget: 1.0 }) {
-    if (budget.inMilliseconds > 1.0)
-      budget = new Duration(milliseconds: 1.0);
-    _addTask(callback: callback, budget: budget, bits: IdleTask, priority: IdlePriority, queue: _idleQueue);
-  }
-
-  factory beforePaint(TimerCallback callback, { int priority: 0 }) {
-    _addTask(callback: callback, budget: new Duration(milliseconds: 1.0), bits: PaintTask, priority: priority, queue: _paintQueue);
-  }
-
-  factory nextFrame(TimerCallback callback, { int priority: 0 }) {
-    _addTask(callback: callback, budget: new Duration(milliseconds: 1.0), bits: PaintTask, priority: priority, queue: _nextPaintQueue);
-  }
-}
-```
-
-
-Easing Functions
-----------------
-
-```dart
-// part of the framework, not dart:sky
-
-typedef void AnimationCallback();
-
-abstract class EasingFunction {
-  EasingFunction({double duration: 0.0, AnimationCallback completionCallback: null });
-  double getFactor(Float time);
-  // calls completionCallback if time >= duration
-  // then returns a number ostensibly in the range 0.0 to 1.0
-  // (but it could in practice go outside this range, e.g. for
-  // animation styles that overreach then come back)
-}
-```
-
-If you want to have two animations simultaneously, e.g. two
-transforms, then you can add to the RenderNode's overrideStyles a
-StyleValue that combines other StyleValues, e.g. a
-"TransformStyleValueCombinerStyleValue", and then add to it the
-regular animated StyleValues, e.g. multiple
-"AnimatedTransformStyleValue" objects. A framework API could make
-setting all that up easy, given the right underlying StyleValue
-classes.