Revert "[framework] SliverDecoration" (#107561)

Author: Jonah Williams

packages/flutter/lib/src/painting/box_decoration.dart

@@ -68,8 +68,6 @@ import 'image_provider.dart';
 ///
 ///  * [DecoratedBox] and [Container], widgets that can be configured with
 ///    [BoxDecoration] objects.
-///  * [SliverDecoration],a widget that can be configured with [BoxDecoration]
-///    objects that is specialized for rendering with slivers.
 ///  * [CustomPaint], a widget that lets you draw arbitrary graphics.
 ///  * [Decoration], the base class which lets you define other decorations.
 class BoxDecoration extends Decoration {

packages/flutter/lib/src/widgets/container.dart

@@ -52,7 +52,6 @@ import 'image.dart';
 ///  * [Decoration], which you can extend to provide other effects with
 ///    [DecoratedBox].
 ///  * [CustomPaint], another way to draw custom effects from the widget layer.
-///  * [SliverDecoration], which paints a [Decoration] around a sliver.
 class DecoratedBox extends SingleChildRenderObjectWidget {
   /// Creates a widget that paints a [Decoration].
   ///

packages/flutter/lib/src/widgets/sliver_decoration.dart

@@ -119,7 +119,6 @@ export 'src/widgets/shortcuts.dart';
 export 'src/widgets/single_child_scroll_view.dart';
 export 'src/widgets/size_changed_layout_notifier.dart';
 export 'src/widgets/sliver.dart';
-export 'src/widgets/sliver_decoration.dart';
 export 'src/widgets/sliver_fill.dart';
 export 'src/widgets/sliver_layout_builder.dart';
 export 'src/widgets/sliver_persistent_header.dart';