Move to unreleased version of dartdoc to avoid crashes on constructor tearoffs.

The version is intended to match up with dart-lang/dartdoc#2768.

Change-Id: Ibe32cda1b6743bc17faf559486cca6f057977408
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/211960
Reviewed-by: Phil Quitslund <[email protected]>
Commit-Queue: Janice Collins <[email protected]>

Author: jcollins-g

DEPS

@@ -105,7 +105,7 @@ vars = {
   # For more details, see https://github.com/dart-lang/sdk/issues/30164
   "dart_style_rev": "14d9b6fd58cc4744676c12be3cc5eee2a779db82",
 
-  "dartdoc_rev" : "a4ca86f9bf732d7adc4506f7373e0ed63251b646",
+  "dartdoc_rev" : "348cbd7204645f99074bf7873af8b6ba6d34ceb0",
   "devtools_rev" : "2b47d9ed486479153ca2fd038000950674ed1beb",
   "jsshell_tag": "version:88.0",
   "ffi_rev": "4dd32429880a57b64edaf54c9d5af8a9fa9a4ffb",