Revert "Bump pub to ec35d46261b610e558dfd0d8525ca3fc8387b4b7"

This reverts commit 78636aa.

Reason for revert: This breaks the google3 roll. We need to roll frontend_server_client first.

Original change's description:
> Bump pub to ec35d46261b610e558dfd0d8525ca3fc8387b4b7
>
> Changes:
> ```
> > git log --format="%C(auto) %h %s" ac7db6c..ec35d46
>  https://dart.googlesource.com/pub.git/+/ec35d462 Fix null-safety warning in dart.dart (#3514)
>  https://dart.googlesource.com/pub.git/+/7d30cf0b Allow pubspec key 'funding' (#3529)
>  https://dart.googlesource.com/pub.git/+/8ff63a8e Fix remaining usages of path.prettyUri on git uris (#3524)
>  https://dart.googlesource.com/pub.git/+/bc32a30e Fix typo "exitcode" (#3511)
>
> ```
>
> Diff: https://dart.googlesource.com/pub.git/+/ac7db6c07318efa4a8712110275eaf70f96a6d00~..ec35d46261b610e558dfd0d8525ca3fc8387b4b7/
> Change-Id: I535f4fab8940ee8400ef75369d35fb4c1ee3adab
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/255990
> Reviewed-by: Sarah Zakarias <[email protected]>
> Commit-Queue: Sigurd Meldgaard <[email protected]>

[email protected],[email protected]

Change-Id: I9f46b5a63f8c3f0b11a9fe1d348696b1f988e5ca
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/256080
Reviewed-by: Sigurd Meldgaard <[email protected]>
Commit-Queue: Sigurd Meldgaard <[email protected]>
Reviewed-by: Jonas Jensen <[email protected]>

CHANGELOG.md

@@ -106,7 +106,6 @@ Updated the Linter to `1.27.0`, which includes changes that
 
 - Remove remaining support for `.packages` files. The flag
   `--legacy-packages-file` is no longer supported.
-- Support a new field `funding` in pubspec.yaml.
 
 #### dart2js
 

DEPS

@@ -136,7 +136,7 @@ vars = {
   "ply_rev": "604b32590ffad5cbb82e4afef1d305512d06ae93",
   "pool_rev": "fa84ddd0e39f45bf3f09dcc5d6b9fbdda7820fef",
   "protobuf_rev": "8337a7910fef805214e5aae35a98abd481d87a18",
-  "pub_rev": "ec35d46261b610e558dfd0d8525ca3fc8387b4b7", # manually rev'd
+  "pub_rev": "ac7db6c07318efa4a8712110275eaf70f96a6d00", # manually rev'd
   "pub_semver_rev": "9fd28757ba45961ac5449e0f2b0020670e921475",
   "root_certificates_rev": "692f6d6488af68e0121317a9c2c9eb393eb0ee50",
   "shelf_rev": "0965d864d0e6c66d5bb6daece400e80484640bd5",