Bump dartdoc to 34561d6ebf5fa89ca1f93b981de96a75ff573562

Changes:
```
> git log --format="%C(auto) %h %s" f0d2276..34561d6
 https://dart.googlesource.com/dartdoc.git/+/34561d6e Migrate some linkedName tests for types to be unit tests. (4007)
 https://dart.googlesource.com/dartdoc.git/+/026aa2a1 Clean up theme styling and improve accessibility of theme toggle (4005)
 https://dart.googlesource.com/dartdoc.git/+/766f61ed Utilize scss nesting in `/styles/dartdoc` (4003)
 https://dart.googlesource.com/dartdoc.git/+/02cfbe11 Rename DartDocResolvedLibrary.element2 -> element (4004)
 https://dart.googlesource.com/dartdoc.git/+/184311c0 Bump to 8.3.3 (4002)
 https://dart.googlesource.com/dartdoc.git/+/85028457 Rename ModelElement field element2 -> element (4000)
 https://dart.googlesource.com/dartdoc.git/+/f0c5210b Update style of GFM alerts for improved accessibility and consistency (4001)
 https://dart.googlesource.com/dartdoc.git/+/eb188add Remove element model migration detritus (3999)
 https://dart.googlesource.com/dartdoc.git/+/9680d369 Move a test case from e2e tests to unit tests. (3998)
 https://dart.googlesource.com/dartdoc.git/+/96f18b49 Elements. Migrate lib/src/model/extension.dart (3994)
 https://dart.googlesource.com/dartdoc.git/+/b8c3f02e Elements. Migrate to Element2 (3991)
 https://dart.googlesource.com/dartdoc.git/+/c386407e Update to analyzer 7.3.0 (3992)
 https://dart.googlesource.com/dartdoc.git/+/75d1fd77 Elements. Remove 'element' from ModelElement (3990)
 https://dart.googlesource.com/dartdoc.git/+/03a5eccc Migrate library element model (3989)
 https://dart.googlesource.com/dartdoc.git/+/b8b63d1a Migrate Constructor element model (3987)
 https://dart.googlesource.com/dartdoc.git/+/a1e234e1 Elements. Migrate lib/src/model/model_element.dart (3988)
 https://dart.googlesource.com/dartdoc.git/+/b4242c7e Elements. Migrate lib/src/model/package_graph.dart (3986)
 https://dart.googlesource.com/dartdoc.git/+/bee02767 Migrate TopLevelVariable and GetterSetterCombo element model (3985)
 https://dart.googlesource.com/dartdoc.git/+/9366e018 Elements. Migrate lib/src/model/accessor.dart (3984)
 https://dart.googlesource.com/dartdoc.git/+/814fbec6 Migrate TypeParameter and Warnings element model (3983)
 https://dart.googlesource.com/dartdoc.git/+/237cd350 Migrate AOT renderers element model (3982)
 https://dart.googlesource.com/dartdoc.git/+/71e78fa7 Migrate codegen_runtime_renderer element model (3981)
 https://dart.googlesource.com/dartdoc.git/+/0bf3f8ee Elements. Migrate to Element2 (3980)
 https://dart.googlesource.com/dartdoc.git/+/1b6fb13f Bump the github-actions group with 2 updates (3979)

```

Diff: https://dart.googlesource.com/dartdoc.git/+/f0d2276e57c96717e625964ea0385a30f2237e62..34561d6ebf5fa89ca1f93b981de96a75ff573562/
Change-Id: Ic0e395f0b00f971d8b2f9bc8a0e47dd1b378caa4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/411800
Auto-Submit: Devon Carew <[email protected]>
Reviewed-by: Konstantin Shcheglov <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: devoncarew

DEPS

@@ -130,7 +130,7 @@ vars = {
   # 'tools/rev_sdk_deps.dart' will rev pkg dependencies to their latest; put an
   # EOL comment after a dependency to instead pin at the current revision.
   "core_rev": "0b2bd3fcd7f3e082f4cc9b14c19ffa93894b85ae",
-  "dartdoc_rev": "f0d2276e57c96717e625964ea0385a30f2237e62",
+  "dartdoc_rev": "34561d6ebf5fa89ca1f93b981de96a75ff573562",
   "ecosystem_rev": "fe4979bc6466de62eaf30b2bf59a78b4bffa3c5b",
   "flute_rev": "e4ea0459a7debae5e9592c85141707b01fac86c9",
   "glob_rev": "043796be996190473b397fa2fecfa34bb91376fb",