Bump pub to 6fdcd and webdev to 637b4

Bump pub to 6fdcdd4357645817e7d7027ee2157ed68ef69c53

Changes:
```
> git log --format="%C(auto) %h %s" 6ac42d7..6fdcdd4
 https://dart.googlesource.com/pub.git/+/6fdcdd43 Support `--native-assets` in kernel compilation commands (#3667)
 https://dart.googlesource.com/pub.git/+/7202dd5e Fix error message for missing transitive dependency (#3196)
 https://dart.googlesource.com/pub.git/+/ab3304e1 Ignore analysis_options.yaml everywhere (#3666)
 https://dart.googlesource.com/pub.git/+/54e0b1eb Only check for sdk updates during resolveExecutable (#3665)
 https://dart.googlesource.com/pub.git/+/327d9ee8 Fix global activate --git-ref (#3656)
 https://dart.googlesource.com/pub.git/+/1485d60c Add env var flag to
override stdout.hasTerminal for output animations (#3658)
 https://dart.googlesource.com/pub.git/+/13ca9de1 Fix escapeShellArgument (#3663)
 https://dart.googlesource.com/pub.git/+/75c671c7 Allow adding from multiple sources (#3571)
 https://dart.googlesource.com/pub.git/+/1acfd4f7 dart pub get --enforce-lockfile (#3637)
 https://dart.googlesource.com/pub.git/+/9810fc6f Suggest using 2.12 as lower-bound SDK constraint (#3660)
 https://dart.googlesource.com/pub.git/+/f481f27a Add a README.md to the pub cache after command ends (#3650)
 https://dart.googlesource.com/pub.git/+/d54d52d3 Have executableForCommand rerun pub get if sdk changed minor version (#3652)
 https://dart.googlesource.com/pub.git/+/ea986525 Delete move.yml (#3648)

```

Diff: https://dart.googlesource.com/pub.git/+/6ac42d7644dedfcc500147ab47886eecab4b1b38~..6fdcdd4357645817e7d7027ee2157ed68ef69c53/

Bump webdev to 637b406f325669507b5c1048c19a7c0083c1bd6e

Changes:
```
> git log --format="%C(auto) %h %s" 3ec168f..637b406
 https://dart.googlesource.com/webdev.git/+/637b406 Support `--native-assets` in `FrontendServerClient` (#1797)
 https://dart.googlesource.com/webdev.git/+/a19d563 Save debug information in `chrome.storage` after a Dart app loads  (#1791)
 https://dart.googlesource.com/webdev.git/+/9cc10d4 Connect to a `chrome.runtime` port to keep the service worker alive  (#1789)

```
Diff: https://dart.googlesource.com/webdev.git/+/3ec168f6815af9d5f11278111d147bc82c0755c3~..637b406f325669507b5c1048c19a7c0083c1bd6e/


Update CHANGELOG


Bump pub to 6fdcdd4357645817e7d7027ee2157ed68ef69c53

Changes:
```
> git log --format="%C(auto) %h %s" 6ac42d7..6fdcdd4
 https://dart.googlesource.com/pub.git/+/6fdcdd43 Support `--native-assets` in kernel compilation commands (#3667)
 https://dart.googlesource.com/pub.git/+/7202dd5e Fix error message for missing transitive dependency (#3196)
 https://dart.googlesource.com/pub.git/+/ab3304e1 Ignore analysis_options.yaml everywhere (#3666)
 https://dart.googlesource.com/pub.git/+/54e0b1eb Only check for sdk updates during resolveExecutable (#3665)
 https://dart.googlesource.com/pub.git/+/327d9ee8 Fix global activate --git-ref (#3656)
 https://dart.googlesource.com/pub.git/+/1485d60c Add env var flag to override stdout.hasTerminal for output animations (#3658)
 https://dart.googlesource.com/pub.git/+/13ca9de1 Fix escapeShellArgument (#3663)
 https://dart.googlesource.com/pub.git/+/75c671c7 Allow adding from multiple sources (#3571)
 https://dart.googlesource.com/pub.git/+/1acfd4f7 dart pub get --enforce-lockfile (#3637)
 https://dart.googlesource.com/pub.git/+/9810fc6f Suggest using 2.12 as lower-bound SDK constraint (#3660)
 https://dart.googlesource.com/pub.git/+/f481f27a Add a README.md to the pub cache after command ends (#3650)
 https://dart.googlesource.com/pub.git/+/d54d52d3 Have executableForCommand rerun pub get if sdk changed minor version (#3652)
 https://dart.googlesource.com/pub.git/+/ea986525 Delete move.yml (#3648)

```

Diff: https://dart.googlesource.com/pub.git/+/6ac42d7644dedfcc500147ab47886eecab4b1b38~..6fdcdd4357645817e7d7027ee2157ed68ef69c53/
Change-Id: I65b928479b44f08305853078b0f34a6b66602709
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/271709
Auto-Submit: Sigurd Meldgaard <sigurdm@google.com>
Reviewed-by: Jonas Jensen <jonasfj@google.com>
Commit-Queue: Jonas Jensen <jonasfj@google.com>

CHANGELOG.md

@@ -261,20 +261,29 @@ Updated the Linter to `1.30.0`, which includes changes that
   These will show up in the lock file on the first run of `dart pub get`.
 
   See https://dart.dev/go/content-hashes for more details.
+- New flag `dart pub get --enforce-lockfile` will fetch dependencies, but fail
+  if anything deviates from `pubspec.lock`. Useful for ensuring reproducible runs
+  in CI and production.
 - Remove remaining support for `.packages` files. The flag
   `--legacy-packages-file` is no longer supported.
 - The client will now default to the `pub.dev` repository instead of `pub.dartlang.org`.
-  This will cause a change in pubspec.lock.
-- Support a new field [`funding`](https://dart.dev/tools/pub/pubspec#funding) in pubspec.yaml.
+  This will cause a change in `pubspec.lock`.
+- Support a new field [`funding`](https://dart.dev/tools/pub/pubspec#funding) in `pubspec.yaml`.
 - Validate the CRC32c checksum of downloaded archives and retry on failure.
 - `dart pub add foo:<constraint>` with an existing dependency will now update
   the constraint rather than fail.
-- Update `dart pub publish` to allow `dependency_overrides` in pubspec.yaml.
+- Update `dart pub publish` to allow `dependency_overrides` in `pubspec.yaml`.
   They will still cause a publication warning.
   Note that only `dependency_overrides` from the root package effect resolution.
 - Update `dart pub publish` to require a working resolution.
   If publishing a breaking release of mutually dependent packages use `dependency_overrides`
   to obtain a resolution.
+- `dart pub add` will now allow adding multiple packages from any source using the same YAML syntax as in `pubspec.yaml`.
+
+  For example:
+  ```
+  $ dart pub add retry:^1.0.0 'dev:foo{"git":"https://github.com/foo/foo"}'
+  ```
 - `dart pub publish` will now give a warning if `dart analyze` reports any diagnostics.
 - `dart pub get` now fails gracefully when run from inside the pub-cache.
 - `dart pub publish` now shows the file sizes of large files in your package to

DEPS

@@ -152,7 +152,7 @@ vars = {
   "ply_rev": "604b32590ffad5cbb82e4afef1d305512d06ae93",
   "pool_rev": "1ea5b031cfda37786d305292cb8104dffb45d9ae",
   "protobuf_rev": "ae90e53cd690edbfc72fa6c293fdb7b4a09ee0a2",
-  "pub_rev": "6ac42d7644dedfcc500147ab47886eecab4b1b38", # manually rev'd
+  "pub_rev": "6fdcdd4357645817e7d7027ee2157ed68ef69c53", # manually rev'd
   "pub_semver_rev": "28159b8c5b96fc2709d0904389d7932880f68659", # b/258766867
   "root_certificates_rev": "692f6d6488af68e0121317a9c2c9eb393eb0ee50",
   "shelf_rev": "1c2104737973715426035c11ba840c7f23d8f186",
@@ -176,7 +176,7 @@ vars = {
   "web_components_rev": "8f57dac273412a7172c8ade6f361b407e2e4ed02",
   "web_socket_channel_rev": "1b0561cfec8ff7e9465896eb340ea3c382b59393",
   "WebCore_rev": "bcb10901266c884e7b3740abc597ab95373ab55c",
-  "webdev_rev": "3ec168f6815af9d5f11278111d147bc82c0755c3",
+  "webdev_rev": "637b406f325669507b5c1048c19a7c0083c1bd6e",
   "webdriver_rev": "336dd3d1208d0b390ac437a785a78760ca7cac7d",
   "webkit_inspection_protocol_rev": "ddb624cd85954dd384056cc253a8fc2b9da5364d",
   "yaml_edit_rev": "299f74594ff9fda412c1da5c0b5d5231d0c6fc42",