Redo: Rewrite MouseTracker's tracking and notifying algorithm (#42486)

* Revert "Revert "Rewrite MouseTracker's tracking and notifying algorithm (#42031)" (#42478)"

This reverts commit eede7929.

* Fix tests

packages/flutter/lib/src/foundation/diagnostics.dart

@@ -2435,7 +2435,7 @@ class ObjectFlagProperty<T> extends DiagnosticsProperty<T> {
 ///
 /// See also:
 ///
-///  * [ObjectFlagSummary], which provides similar functionality but accepts
+///  * [ObjectFlagProperty], which provides similar functionality but accepts
 ///    only one flag, and is preferred if there is only one entry.
 ///  * [IterableProperty], which provides similar functionality describing
 ///    the values a collection of objects.

packages/flutter/test/widgets/mouse_region_test.dart

@@ -836,7 +836,7 @@ void main() {
       // Move to the overlapping area
       await gesture.moveTo(const Offset(75, 75));
       await tester.pumpAndSettle();
-      expect(logs, <String>['enterA', 'enterC', 'enterB']);
+      expect(logs, <String>['enterA', 'enterB', 'enterC']);
       logs.clear();
 
       // Move to the B only area
@@ -866,7 +866,7 @@ void main() {
       // Move out
       await gesture.moveTo(const Offset(160, 160));
       await tester.pumpAndSettle();
-      expect(logs, <String>['exitA', 'exitB', 'exitC']);
+      expect(logs, <String>['exitC', 'exitB', 'exitA']);
     });
 
     testWidgets('an opaque one should prevent MouseRegions behind it receiving pointers', (WidgetTester tester) async {
@@ -890,13 +890,13 @@ void main() {
       // Move to the B only area
       await gesture.moveTo(const Offset(25, 75));
       await tester.pumpAndSettle();
-      expect(logs, <String>['enterB', 'exitC']);
+      expect(logs, <String>['exitC', 'enterB']);
       logs.clear();
 
       // Move back to the overlapping area
       await gesture.moveTo(const Offset(75, 75));
       await tester.pumpAndSettle();
-      expect(logs, <String>['enterC', 'exitB']);
+      expect(logs, <String>['exitB', 'enterC']);
       logs.clear();
 
       // Move to the C only area
@@ -914,7 +914,7 @@ void main() {
       // Move out
       await gesture.moveTo(const Offset(160, 160));
       await tester.pumpAndSettle();
-      expect(logs, <String>['exitA', 'exitC']);
+      expect(logs, <String>['exitC', 'exitA']);
     });
 
     testWidgets('opaque should default to true', (WidgetTester tester) async {
@@ -938,7 +938,7 @@ void main() {
       // Move out
       await gesture.moveTo(const Offset(160, 160));
       await tester.pumpAndSettle();
-      expect(logs, <String>['exitA', 'exitC']);
+      expect(logs, <String>['exitC', 'exitA']);
     });
   });