Remove unused function (#2808)

diff --git a/lib/src/solver/package_lister.dart b/lib/src/solver/package_lister.dart
index f57573d..087c958 100644
--- a/lib/src/solver/package_lister.dart
+++ b/lib/src/solver/package_lister.dart
@@ -447,7 +447,5 @@
   @override
   Future<Pubspec> doDescribe(PackageId id) => throw _unsupported;
   @override
-  Future get(PackageId id, String symlink) => throw _unsupported;
-  @override
   String getDirectory(PackageId id) => throw _unsupported;
 }
diff --git a/lib/src/source.dart b/lib/src/source.dart
index ce35fb0..50e631a 100644
--- a/lib/src/source.dart
+++ b/lib/src/source.dart
@@ -229,10 +229,6 @@
   /// external code should not call this. Instead, call [describe].
   Future<Pubspec> doDescribe(PackageId id);
 
-  /// Ensures [id] is available locally and creates a symlink at [symlink]
-  /// pointing it.
-  Future get(PackageId id, String symlink);
-
   /// Returns the directory where this package can (or could) be found locally.
   ///
   /// If the source is cached, this will be a path in the system cache.
diff --git a/lib/src/source/cached.dart b/lib/src/source/cached.dart
index 28f903a..0ec9b1f 100644
--- a/lib/src/source/cached.dart
+++ b/lib/src/source/cached.dart
@@ -47,13 +47,6 @@
   /// the system cache.
   Future<Pubspec> describeUncached(PackageId id);
 
-  @override
-  Future get(PackageId id, String symlink) {
-    return downloadToSystemCache(id).then((pkg) {
-      createPackageSymlink(id.name, pkg.dir, symlink);
-    });
-  }
-
   /// Determines if the package identified by [id] is already downloaded to the
   /// system cache.
   bool isInSystemCache(PackageId id) => dirExists(getDirectory(id));
diff --git a/lib/src/source/path.dart b/lib/src/source/path.dart
index 45b827a..1d06496 100644
--- a/lib/src/source/path.dart
+++ b/lib/src/source/path.dart
@@ -181,15 +181,6 @@
   }
 
   @override
-  Future get(PackageId id, String symlink) {
-    return Future.sync(() {
-      var dir = _validatePath(id.name, id.description);
-      createPackageSymlink(id.name, dir, symlink,
-          relative: id.description['relative']);
-    });
-  }
-
-  @override
   String getDirectory(PackageId id) => id.description['path'];
 
   /// Ensures that [description] is a valid path description and returns a
diff --git a/lib/src/source/sdk.dart b/lib/src/source/sdk.dart
index 38ae7ec..ec201f2 100644
--- a/lib/src/source/sdk.dart
+++ b/lib/src/source/sdk.dart
@@ -7,7 +7,6 @@
 import 'package:pub_semver/pub_semver.dart';
 
 import '../exceptions.dart';
-import '../io.dart';
 import '../package_name.dart';
 import '../pubspec.dart';
 import '../sdk.dart';
@@ -89,11 +88,6 @@
       Pubspec.load(_verifiedPackagePath(package), systemCache.sources,
           expectedName: package.name);
 
-  @override
-  Future get(PackageId id, String symlink) async {
-    createPackageSymlink(id.name, _verifiedPackagePath(id), symlink);
-  }
-
   /// Returns the path for the given [package].
   ///
   /// Throws a [PackageNotFoundException] if [package]'s SDK is unavailable or
diff --git a/lib/src/source/unknown.dart b/lib/src/source/unknown.dart
index ac43447..a9ae1f2 100644
--- a/lib/src/source/unknown.dart
+++ b/lib/src/source/unknown.dart
@@ -69,10 +69,6 @@
   Future<Pubspec> doDescribe(PackageId id) => throw UnsupportedError(
       "Cannot describe a package from unknown source '${source.name}'.");
 
-  @override
-  Future get(PackageId id, String symlink) =>
-      throw UnsupportedError("Cannot get an unknown source '${source.name}'.");
-
   /// Returns the directory where this package can be found locally.
   @override
   String getDirectory(PackageId id) => throw UnsupportedError(