Remove Link depenedency in Tagging debug class.

Change-Id: Iabd0edb24eee278c3f12a9f61fe535645e1f26d6
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/208761
Commit-Queue: Riley Porter <rileyporter@google.com>
Reviewed-by: Sigmund Cherem <sigmund@google.com>

Author: rileyporter

pkg/kernel/lib/text/indentation.dart

@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'package:_fe_analyzer_shared/src/util/link.dart' show Link;
-
 /// Indentation utility class. Should be used as a mixin in most cases.
 class Indentation {
   /// The current indentation string.
@@ -54,19 +52,17 @@ class Indentation {
 
 abstract class Tagging<N> implements Indentation {
   StringBuffer sb = new StringBuffer();
-  Link<String> tagStack = const Link<String>();
+  List<String> tagStack = [];
 
   void pushTag(String tag) {
-    tagStack = tagStack.prepend(tag);
+    tagStack.add(tag);
     indentMore();
   }
 
   String popTag() {
     assert(!tagStack.isEmpty);
-    String tag = tagStack.head;
-    tagStack = tagStack.tail!;
     indentLess();
-    return tag;
+    return tagStack.removeLast();
   }
 
   /// Adds given string to result string.

pkg/kernel/pubspec.yaml

@@ -8,8 +8,6 @@ publish_to: none
 environment:
   sdk: '>=2.12.0 <3.0.0'
 dependencies:
-  _fe_analyzer_shared:
-    path: ../_fe_analyzer_shared
 dev_dependencies:
   args: '>=0.13.4 <2.0.0'
   expect: