Fix BidirectionalIterator deprecation warning and roll engine to a1dd50405992 (#106595)

* a1dd50405 Roll Dart SDK from 692562354d6d to 48e3f8edb811 (3 revisions) (flutter/engine#34282)

* Fix BidirectionalIterator deprecation warning

* Remove override for movePrevious
Co-authored-by: engine-flutter-autoroll <engine-flutter-autoroll@skia.org>

bin/internal/engine.version

-4446e3edda6a3ef9dd34afcabb5ebff0747d5f93
+a1dd504059925c9925ad9d36f0cf67ad8ea62eb0

packages/flutter/lib/src/rendering/editable.dart

@@ -112,7 +112,7 @@ class TextSelectionPoint {
 /// the [VerticalCaretMovementRun] must not be used. The [isValid] property must
 /// be checked before calling [movePrevious] and [moveNext], or accessing
 /// [current].
-class VerticalCaretMovementRun extends BidirectionalIterator<TextPosition> {
+class VerticalCaretMovementRun extends Iterator<TextPosition> {
   VerticalCaretMovementRun._(
     this._editable,
     this._lineMetrics,
@@ -186,7 +186,9 @@ class VerticalCaretMovementRun extends BidirectionalIterator<TextPosition> {
     return true;
   }
 
-  @override
+  /// Move back to the previous element.
+  ///
+  /// Returns true and updates [current] if successful.
   bool movePrevious() {
     assert(isValid);
     if (_currentLine <= 0) {