Roll dart_style into the SDK.

This includes a single commit which fixes:

dart-lang/dart_style#1224

This doesn't need to be coordinated with a pre-built SDK update.

Change-Id: Ifaabfde1d0d3dc180cf65a1052ba8dcff3324013
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/306122
Reviewed-by: Alexander Thomas <athom@google.com>
Commit-Queue: Bob Nystrom <rnystrom@google.com>
Auto-Submit: Bob Nystrom <rnystrom@google.com>

CHANGELOG.md

@@ -59,6 +59,12 @@
 
 [#52334]: https://dartbug.com/52334
 
+### Tools
+
+#### Formatter
+
+- Correctly handle nullable empty record types (`()?`).
+
 ## 3.0.1
 
 ### Tools

DEPS

@@ -136,7 +136,7 @@ vars = {
  # and land the review.
  #
  # For more details, see https://github.com/dart-lang/sdk/issues/30164.
- "dart_style_rev": "a36eb2030765592701ec0f54b4085c0932c39991", # disable rev_sdk_deps.dart
+ "dart_style_rev": "2956b1a705953f880a5dae9d3a0969df0fc45e99", # disable rev_sdk_deps.dart
  "dartdoc_rev": "950898f5ffea617bc572687c15cf51b2d6f05dad",
  "ffi_rev": "7f4acbd7532d94a793452030ff96bfef8cd96b68",
  "file_rev": "5d9a6027756b5846e8f5380f983390f61f564a75",