Complain about built-in identifiers.

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

Index: pkg/front_end/lib/src/fasta/scanner/token.dart
diff --git a/pkg/front_end/lib/src/fasta/scanner/token.dart b/pkg/front_end/lib/src/fasta/scanner/token.dart
index 6cacd012d2b5b5260dfdc555b6dcdb902a9094c9..67dacdc330af37923ca8c30896f7f95ed6a4bfec 100644
--- a/pkg/front_end/lib/src/fasta/scanner/token.dart
+++ b/pkg/front_end/lib/src/fasta/scanner/token.dart
@@ -123,6 +123,8 @@ abstract class Token {
   int get charEnd => charOffset + charCount;
 
   bool get isEof => false;
+
+  bool get isBuiltInIdentifier => false;
 }
 
 /**
@@ -174,6 +176,10 @@ class KeywordToken extends Token {
 
   bool isIdentifier() => keyword.isPseudo || keyword.isBuiltIn;
 
+  bool get isBuiltInIdentifier {
+    return keyword.isBuiltIn || identical("deferred", lexeme);

[danrubel, 2017/03/14 15:21:43]

Similar to what Paul recommended in the fasta.Keyword CL (see link below), I
suggest we add the following comment here.

// TODO: remove `identical("deferred", lexeme)` once dartbug.com/29069 is fixed.


https://codereview.chromium.org/2746023003/diff/40001/pkg/front_end/lib/src/f...

[ahe, 2017/03/14 15:24:35]

Yes. That's how I knew about this case :-)

I'll add the todo.

+  }
+
   String toString() => "KeywordToken($lexeme)";
 }