Refactor comment reference parsing, away from stack.

Now that comment reference parsing is done entirely in ast_builder, we
can simplify the implementation.

Work towards #50702

Change-Id: I0650706dfe31542454c7bc9832ec6104c141bd5d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/316643
Commit-Queue: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Paul Berry <paulberry@google.com>

pkg/_fe_analyzer_shared/lib/src/parser/forwarding_listener.dart

@@ -1407,23 +1407,6 @@ class ForwardingListener implements Listener {
     listener?.handleMixinWithClause(withKeyword);
   }
 
-  @override
-  void handleCommentReference(
-      Token? newKeyword,
-      Token? firstToken,
-      Token? firstPeriod,
-      Token? secondToken,
-      Token? secondPeriod,
-      Token thirdToken) {
-    listener?.handleCommentReference(newKeyword, firstToken, firstPeriod,
-        secondToken, secondPeriod, thirdToken);
-  }
-
-  @override
-  void handleCommentReferenceText(String referenceSource, int referenceOffset) {
-    listener?.handleCommentReferenceText(referenceSource, referenceOffset);
-  }
-
   @override
   void handleConditionalExpressionColon() {
     listener?.handleConditionalExpressionColon();
@@ -1752,11 +1735,6 @@ class ForwardingListener implements Listener {
     listener?.handleNoArguments(token);
   }
 
-  @override
-  void handleNoCommentReference() {
-    listener?.handleNoCommentReference();
-  }
-
   @override
   void handleNoConstructorReferenceContinuationAfterTypeArguments(Token token) {
     listener?.handleNoConstructorReferenceContinuationAfterTypeArguments(token);

pkg/_fe_analyzer_shared/lib/src/parser/listener.dart

@@ -2287,39 +2287,6 @@ class Listener implements UnescapeErrorListener {
     logEvent("Script");
   }
 
-  /// A single comment reference has been found
-  /// where [referenceSource] is the text between the `[` and `]`
-  /// and [referenceOffset] is the character offset in the token stream.
-  ///
-  /// This event is generated by the parser when the parser's
-  /// `parseCommentReferences` method is called. For further processing,
-  /// a listener may scan the [referenceSource] and then pass the resulting
-  /// token stream to the parser's `parseOneCommentReference` method.
-  void handleCommentReferenceText(String referenceSource, int referenceOffset) {
-    logEvent("CommentReferenceText");
-  }
-
-  /// A single comment reference has been parsed.
-  /// * [newKeyword] may be null.
-  /// * [firstToken] and [firstPeriod] are either both tokens or both
-  ///   `null`.
-  /// * [secondToken] and [secondPeriod] are either both tokens or both `null`.
-  /// * [thirdToken] can be an identifier or an operator.
-  ///
-  /// This event is generated by the parser when the parser's
-  /// `parseOneCommentReference` method is called.
-  void handleCommentReference(
-      Token? newKeyword,
-      Token? firstToken,
-      Token? firstPeriod,
-      Token? secondToken,
-      Token? secondPeriod,
-      Token thirdToken) {}
-
-  /// This event is generated by the parser when the parser's
-  /// `parseOneCommentReference` method is called.
-  void handleNoCommentReference() {}
-
   /// An expression was encountered consisting of type arguments applied to a
   /// subexpression.  This could validly represent any of the following:
   /// - A type literal (`var x = List<int>;`)