Fix typo in overlay.dart documentation comment (flutter#176612)

Changed "resulting" to "result". 

_Putting a CompositedTransformFollower between the OverlayPortal and the
Overlay may result<s>ing</s> in an incorrect child paint transform being
provided to the overlayChildBuilder and will cause an assertion in debug
mode._


## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [ ] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

**Note**: The Flutter team is currently trialing the use of [Gemini Code
Assist for
GitHub](https://developers.google.com/gemini-code-assist/docs/review-github-code).
Comments from the `gemini-code-assist` bot should not be taken as
authoritative feedback from the Flutter team. If you find its comments
useful you can update your code accordingly, but if you are unsure or
disagree with the feedback, please feel free to wait for a Flutter team
member's review for guidance on which automated comments should be
addressed.

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[Tree Hygiene]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

Co-authored-by: Justin McCandless <jmccandless@google.com>
Co-authored-by: Victor Sanni <victorsanniay@gmail.com>

Author: 3 people

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

@@ -1846,7 +1846,7 @@ class OverlayPortal extends StatefulWidget {
   /// exception is the [CompositedTransformFollower] widget, whose [RenderObject]
   /// only establishes the paint transform when composited. Putting a
   /// [CompositedTransformFollower] between the [OverlayPortal] and the [Overlay]
-  /// may resulting in an incorrect child paint transform being provided to the
+  /// may result in an incorrect child paint transform being provided to the
   /// `overlayChildBuilder` and will cause an assertion in debug mode.
   ///
   /// The [overlayLocation] sets which [Overlay] this widget attaches the widget