fix an issue with reloading when paused at a breakpoint (#9733)

* fix an issues with reloading when paused at a breakpoint

* update docs

packages/flutter_tools/lib/src/vmservice.dart

diff --git a/packages/flutter_tools/lib/src/vmservice.dart b/packages/flutter_tools/lib/src/vmservice.dart
index e8447c2..9cf7675 100644
--- a/packages/flutter_tools/lib/src/vmservice.dart
+++ b/packages/flutter_tools/lib/src/vmservice.dart
@@ -844,6 +844,9 @@
   Isolate get isolate => this;
 
   DateTime startTime;
+
+  /// The last pause event delivered to the isolate. If the isolate is running,
+  /// this will be a resume event.
   ServiceEvent pauseEvent;
 
   final Map<String, ServiceObject> _cache = <String, ServiceObject>{};