Revert "Bring in the latest pub."

CHANGELOG.md

 ## 1.23.0
 
 ### Language
 * Allow using URI strings in `part of` declarations to refer to the
   importing library.
 
 ### Core library changes
 * `dart:core`: Added `Uri.isScheme` function to check the scheme of a URI.
    Example: `uri.isScheme("http")`. Ignores case when comparing.
 * `dart:core`: Make `UriData.parse` validate its input better.
@@ skipping 20 matching lines @@
       [default Flutter analysis options](https://github.com/flutter/flutter/blob/master/packages/flutter/lib/analysis_options_user.yaml)
       found in `package:flutter`.
     * If in a Bazel workspace, then use the analysis options in `package:dart.analysis_options/default.yaml` if it exists.
     * Use the default analysis options rules.
   * In addition, specific to `dartanalyzer`:
     * an analysis options file can be specified on the command line via `--options` 
       and that file will be used instead of searching for an analysis options file.
     * any analysis option specified on the command line (e.g. `--strong` or `--no-strong`) 
       takes precedence over any corresponding value specified in the analysis options file.
 
-* Pub
-
-  * `pub publish`
-
-    * Warns if a package imports a package that's not a dependency from within
-      `lib/` or `bin/`, or a package that's not a dev dependency from within
-      `test/` or `tool/`.
-
-    * No longer produces "UID too large" errors on OS X. All packages are now
-      uploaded with the user and group names set to "pub".
-
-    * No longer fails with a stack overflow when uploading a package that uses
-      Git submodules.
-
-  * `pub get` and `pub upgrade`
-
-    * Produce more informative error messages if they're run directly in a
-      package that uses Flutter.
-
-    * Properly unlock SDK and path dependencies if they have a new version
-      that's also valid according to the user's pubspec.
 
 ## 1.22.0
 
 ### Language
 
   * Breaking change: ['Generalized tear-offs'](https://github.com/gbracha/generalizedTearOffs/blob/master/proposal.md)
     are no longer supported, and will cause errors. We updated the language spec
     and added warnings in 1.21, and are now taking the last step to fully
     de-support them. They were previously only supported in the VM, and there
     are almost no known uses of them in the wild.
@@ skipping 1653 matching lines @@
     they will keep the Dart process alive until they time out. This fixes the
     handling of persistent connections. Previously, the client would shut down
     immediately after a request.
 
   * **Breaking change:** `HttpServer` no longer compresses all traffic by
     default. The new `autoCompress` property can be set to `true` to re-enable
     compression.
 
 * `dart:isolate`: `Isolate.spawnUri` added the optional `packageRoot` argument,
   which controls how it resolves `package:` URIs.