update analyzer parser tests for fasta scanner

pkg/front_end/lib/src/scanner/token.dart

Index: pkg/front_end/lib/src/scanner/token.dart
diff --git a/pkg/front_end/lib/src/scanner/token.dart b/pkg/front_end/lib/src/scanner/token.dart
index c208c134da19df03cbc4634aaa7f14a5b1a36bef..bdf42dfc038b2c54e2238b6caf23b2748f784511 100644
--- a/pkg/front_end/lib/src/scanner/token.dart
+++ b/pkg/front_end/lib/src/scanner/token.dart
@@ -1230,6 +1230,9 @@ class TokenType {
       '==', 'EQ_EQ', EQUALITY_PRECEDENCE, EQ_EQ_TOKEN,
       isOperator: true, isUserDefinableOperator: true);
 
+  /// The `===` operator is not supported in the Dart language
+  /// but is parsed as such by the scanner to support better recovery
+  /// when a JavaScript code snippet is pasted into a Dart file.
   static const TokenType EQ_EQ_EQ =
       const TokenType('===', 'EQ_EQ_EQ', EQUALITY_PRECEDENCE, EQ_EQ_EQ_TOKEN);