[parser] Enforce module-specific identifier restriction

src/parsing/token.h

Index: src/parsing/token.h
diff --git a/src/parsing/token.h b/src/parsing/token.h
index 7a62b4d9153a399ac546df9496ed5d921d863ed3..f52881b337f81e73b8de10bf4b52bdd85d98950b 100644
--- a/src/parsing/token.h
+++ b/src/parsing/token.h
@@ -146,10 +146,12 @@ namespace internal {
   T(IDENTIFIER, NULL, 0)                                             \
                                                                      \
   /* Future reserved words (ECMA-262, section 7.6.1.2). */           \
-  T(FUTURE_RESERVED_WORD, NULL, 0)                                   \
   T(FUTURE_STRICT_RESERVED_WORD, NULL, 0)                            \
+  /* `await` is a reserved word in module code only */               \
+  K(AWAIT, "await", 0)                                               \
   K(CLASS, "class", 0)                                               \
   K(CONST, "const", 0)                                               \
+  K(ENUM, "enum", 0)                                                 \
   K(EXPORT, "export", 0)                                             \
   K(EXTENDS, "extends", 0)                                           \
   K(IMPORT, "import", 0)                                             \
@@ -171,7 +173,6 @@ namespace internal {
   T(TEMPLATE_SPAN, NULL, 0)                                          \
   T(TEMPLATE_TAIL, NULL, 0)
 
-
 class Token {
  public:
   // All token values.
@@ -195,7 +196,7 @@ class Token {
   }
 
   static bool IsIdentifier(Value tok, LanguageMode language_mode,
-                           bool is_generator) {
+                           bool is_generator, bool is_module) {

[mike3, 2016/02/23 19:29:44]

This method is starting to succumb to the boolean trap. I think we could
refactor this method's signature to accept simply accept a token and a Scope
reference, e.g.:

    static bool IsIdentifier(Value tok, Scope* scope)

...but that may violate a separation of concerns principle.

     switch (tok) {
       case IDENTIFIER:
         return true;
@@ -206,6 +207,8 @@ class Token {
         return is_sloppy(language_mode);
       case YIELD:
         return !is_generator && is_sloppy(language_mode);
+      case AWAIT:
+        return !is_module;
       default:
         return false;
     }