Add CommentToken.parent and implement CommentToken.remove().

pkg/front_end/test/scanner_fasta_test.dart

Index: pkg/front_end/test/scanner_fasta_test.dart
diff --git a/pkg/front_end/test/scanner_fasta_test.dart b/pkg/front_end/test/scanner_fasta_test.dart
index ee1d36af75d35984cb46a4ede4b215ad84245188..b247bab8bf7f023cdea4ec4c6db3f68c9cacb348 100644
--- a/pkg/front_end/test/scanner_fasta_test.dart
+++ b/pkg/front_end/test/scanner_fasta_test.dart
@@ -136,6 +136,74 @@ class ScannerTest_Fasta extends ScannerTestBase {
     expect(token.precedingComments?.lexeme, '// EOF comment');
   }
 
+  void test_CommentToken_remove() {
+    const code = '''
+/// aaa
+/// bbbb
+/// ccccc
+main() {}
+''';
+
+    fasta.Token token;
+    fasta.CommentToken c1;
+    fasta.CommentToken c2;
+    fasta.CommentToken c3;
+
+    void prepareTokens() {
+      token = new fasta.StringScanner(code, includeComments: true).tokenize();
+
+      expect(token.info.kind, fasta.IDENTIFIER_TOKEN);
+
+      c1 = token.precedingCommentTokens;
+      c2 = c1.next;
+      c3 = c2.next;
+      expect(c3.next, isNull);
+
+      expect(c1.parent, token);
+      expect(c2.parent, token);
+      expect(c3.parent, token);
+
+      expect(c1.lexeme, '/// aaa');
+      expect(c2.lexeme, '/// bbbb');
+      expect(c3.lexeme, '/// ccccc');
+    }
+
+    // Remove the first token.
+    {
+      prepareTokens();
+      c1.remove();
+      expect(token.precedingCommentTokens, c2);
+      expect(c2.next, c3);
+      expect(c3.next, isNull);
+    }
+
+    // Remove the second token.
+    {
+      prepareTokens();
+      c2.remove();
+      expect(token.precedingCommentTokens, c1);
+      expect(c1.next, c3);
+      expect(c3.next, isNull);
+    }
+
+    // Remove the last token.
+    {
+      prepareTokens();
+      c3.remove();
+      expect(token.precedingCommentTokens, c1);
+      expect(c1.next, c2);
+      expect(c2.next, isNull);
+    }
+  }
+
+  @override
+  @failingTest
+  void test_incomplete_string_interpolation() {
+    // TODO(danrubel): fix ToAnalyzerTokenStreamConverter_WithListener
+    // to handle synthetic closers in token stream
+    super.test_incomplete_string_interpolation();
+  }
+
   @override
   @failingTest
   void test_mismatched_closer() {
@@ -152,31 +220,6 @@ class ScannerTest_Fasta extends ScannerTestBase {
     super.test_mismatched_opener();
   }
 
-  void test_next_previous() {
-    const source = 'int a; /*1*/ /*2*/ /*3*/ B f(){if (a < 2) {}}';
-    fasta.Token token =
-        new fasta.StringScanner(source, includeComments: true).tokenize();
-    while (!token.isEof) {
-      expect(token.next.previousToken, token);
-      fasta.CommentToken commentToken = token.precedingComments;
-      while (commentToken != null) {
-        if (commentToken.next != null) {
-          expect(commentToken.next.previousToken, commentToken);
-        }
-        commentToken = commentToken.next;
-      }
-      token = token.next;
-    }
-  }
-
-  @override
-  @failingTest
-  void test_incomplete_string_interpolation() {
-    // TODO(danrubel): fix ToAnalyzerTokenStreamConverter_WithListener
-    // to handle synthetic closers in token stream
-    super.test_incomplete_string_interpolation();
-  }
-
   @override
   void test_mismatched_opener_in_interpolation() {
     // When openers and closers are mismatched,
@@ -201,6 +244,23 @@ class ScannerTest_Fasta extends ScannerTestBase {
     expect(openParen2.endToken, same(closeParen2));
   }
 
+  void test_next_previous() {
+    const source = 'int a; /*1*/ /*2*/ /*3*/ B f(){if (a < 2) {}}';
+    fasta.Token token =
+        new fasta.StringScanner(source, includeComments: true).tokenize();
+    while (!token.isEof) {
+      expect(token.next.previousToken, token);
+      fasta.CommentToken commentToken = token.precedingComments;
+      while (commentToken != null) {
+        if (commentToken.next != null) {
+          expect(commentToken.next.previousToken, commentToken);
+        }
+        commentToken = commentToken.next;
+      }
+      token = token.next;
+    }
+  }
+
   @override
   @failingTest
   void test_string_multi_unterminated() {