[parser] Drop undefined as a contextual keyword

Change-Id: I6e8c72ea46e02361b7dd8ae698f3c13aef8a8beb
Reviewed-on: https://chromium-review.googlesource.com/c/1332297
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57462}

src/parsing/scanner-inl.h

@@ -221,8 +221,6 @@ static const Token::Value one_char_tokens[] = {
   KEYWORD("true", Token::TRUE_LITERAL)                      \
   KEYWORD("try", Token::TRY)                                \
   KEYWORD("typeof", Token::TYPEOF)                          \
-  KEYWORD_GROUP('u')                                        \
-  KEYWORD("undefined", Token::UNDEFINED)                    \
   KEYWORD_GROUP('v')                                        \
   KEYWORD("var", Token::VAR)                                \
   KEYWORD("void", Token::VOID)                              \

src/parsing/token.h

@@ -206,8 +206,7 @@ namespace internal {
   C(NAME, "name", 0)                                               \
   C(CONSTRUCTOR, "constructor", 0)                                 \
   C(PRIVATE_CONSTRUCTOR, "#constructor", 0)                        \
-  C(PROTOTYPE, "prototype", 0)                                     \
-  C(UNDEFINED, "undefined", 0)
+  C(PROTOTYPE, "prototype", 0)
 
 class Token {
  public:
@@ -228,7 +227,7 @@ class Token {
   // Predicates
   static bool IsKeyword(Value token) { return token_type[token] == 'K'; }
   static bool IsContextualKeyword(Value token) {
-    return IsInRange(token, GET, UNDEFINED);
+    return IsInRange(token, GET, PROTOTYPE);
   }
 
   static bool IsIdentifier(Value token, LanguageMode language_mode,