Bump pub to 84895ca4c52df5ecc7dd4d439365c3045b7c2165

Changes:
```
> git log --format="%C(auto) %h %s" e184bfc..84895ca
 https://dart.googlesource.com/pub.git/+/84895ca4 Fix fast path check of ensureUpToDate (4271)
 https://dart.googlesource.com/pub.git/+/89e386bc Rewrite `getExecutableForCommand` tests to test with an external process. (4268)
 https://dart.googlesource.com/pub.git/+/7ab4020e Connect to _PUB_TEST_DEFAULT_HOSTED_URL instead of pub.dev when testing (4270)
 https://dart.googlesource.com/pub.git/+/c2592b3e Use lint unreachable_from_main to avoid dead code (4244)
 https://dart.googlesource.com/pub.git/+/a87b84dc Allow invoking `getExecutableForCommand` everywhere in workspace (4257)
 https://dart.googlesource.com/pub.git/+/a284c9b3 Remove debug logging statements (4267)

```

Diff: https://dart.googlesource.com/pub.git/+/e184bfc725793cbbf222fa8d8f96da10c40af24a..84895ca4c52df5ecc7dd4d439365c3045b7c2165/
Change-Id: I1eacbe85bd1016099575af06751205a94f988b3f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/367000
Commit-Queue: Sigurd Meldgaard <sigurdm@google.com>
Reviewed-by: Jonas Jensen <jonasfj@google.com>

DEPS

@@ -169,7 +169,7 @@ vars = {
   "path_rev": "9be79e72be7837fd8b99ae51a69f4c9f04ec29b4",
   "pool_rev": "1a6f2df19d7a24baaf674e032a0310a4f76725de",
   "protobuf_rev": "ccf104dbc36929c0f8708285d5f3a8fae206343e",
-  "pub_rev": "e184bfc725793cbbf222fa8d8f96da10c40af24a", # disable tools/rev_sdk_deps.dart
+  "pub_rev": "84895ca4c52df5ecc7dd4d439365c3045b7c2165", # disable tools/rev_sdk_deps.dart
   "pub_semver_rev": "f57c9c31dfd4e45ce6b11f18ee388e526ba1792a",
   "shelf_rev": "d9f82bf2cdd87e2878cfdc167aa41b9ce87a52d8",
   "source_map_stack_trace_rev": "6834af5e9e4ba880741b1357a5967fee8d90827c",

pkg/dartdev/test/commands/run_test.dart

@@ -547,6 +547,61 @@ void main(List<String> args) => print("$b $args");
     expect(result.exitCode, 255);
   });
 
+  test('workspace', () async {
+    final p = project(
+        sdkConstraint: VersionConstraint.parse('^3.5.0-0'),
+        pubspecExtras: {
+          'workspace': ['pkgs/a', 'pkgs/b']
+        });
+    p.file('pkgs/a/pubspec.yaml', '''
+name: a
+environment:
+  sdk: ^3.5.0-0
+resolution: workspace
+dependencies:
+  b:
+''');
+    p.file('pkgs/b/pubspec.yaml', '''
+name: b
+environment:
+  sdk: ^3.5.0-0
+resolution: workspace
+''');
+    p.file('pkgs/a/bin/a.dart', '''
+main() => print('a:a');
+''');
+    p.file('pkgs/a/bin/tool.dart', '''
+main() => print('a:tool');
+''');
+    p.file('pkgs/b/bin/b.dart', '''
+main() => print('b:b');
+''');
+    expect(
+        await p
+            .run(['run', 'a'], workingDir: path.join(p.dirPath, 'pkgs', 'a')),
+        isA<ProcessResult>()
+            .having((r) => r.exitCode, 'exitCode', 0)
+            .having((r) => r.stdout, 'stdout', 'a:a\n'));
+    expect(
+        await p
+            .run(['run', 'a:a'], workingDir: path.join(p.dirPath, 'pkgs', 'a')),
+        isA<ProcessResult>()
+            .having((r) => r.exitCode, 'exitCode', 0)
+            .having((r) => r.stdout, 'stdout', 'a:a\n'));
+    expect(
+        await p.run(['run', ':tool'],
+            workingDir: path.join(p.dirPath, 'pkgs', 'a')),
+        isA<ProcessResult>()
+            .having((r) => r.exitCode, 'exitCode', 0)
+            .having((r) => r.stdout, 'stdout', 'a:tool\n'));
+    expect(
+        await p
+            .run(['run', 'b'], workingDir: path.join(p.dirPath, 'pkgs', 'a')),
+        isA<ProcessResult>()
+            .having((r) => r.exitCode, 'exitCode', 0)
+            .having((r) => r.stdout, 'stdout', 'b:b\n'));
+  });
+
   group('DDS', () {
     group('disable', () {
       test('dart run simple', () async {

pkg/dartdev/test/commands/test_test.dart

@@ -264,4 +264,44 @@ void main() {
       });
     }
   });
+
+  test('workspace', () async {
+    final p = project(
+        sdkConstraint: VersionConstraint.parse('^3.5.0-0'),
+        pubspecExtras: {
+          'workspace': ['pkgs/a', 'pkgs/b']
+        });
+    p.file('pkgs/a/pubspec.yaml', '''
+name: a
+environment:
+  sdk: ^3.5.0-0
+resolution: workspace
+dependencies:
+  b:
+  test: any
+''');
+    p.file('pkgs/b/pubspec.yaml', '''
+name: b
+environment:
+  sdk: ^3.5.0-0
+resolution: workspace
+''');
+    p.file('pkgs/a/test/a_test.dart', '''
+import 'package:test/test.dart';
+main() {
+  test('works', () {
+    print('testing package a');
+  });
+} 
+''');
+    p.file('pkgs/b/test/b_test.dart', '''
+main() => throw('Test failure');
+''');
+    expect(
+        await p.run(['test'], workingDir: path.join(p.dirPath, 'pkgs', 'a')),
+        isA<ProcessResult>()
+            .having((r) => r.stdout, 'stdout', contains('testing package a\n'))
+            .having((r) => r.stderr, 'stderr', isEmpty)
+            .having((r) => r.exitCode, 'exitCode', 0));
+  });
 }