[parser] Enforce module-specific identifier restriction

src/parsing/preparser.cc

Index: src/parsing/preparser.cc
diff --git a/src/parsing/preparser.cc b/src/parsing/preparser.cc
index d335c8bdcd29433337d1173c9e17b3a1e116a999..9e069b360f72f3c759137144e88af734eda5d449 100644
--- a/src/parsing/preparser.cc
+++ b/src/parsing/preparser.cc
@@ -38,8 +38,10 @@ void PreParserTraits::ReportMessageAt(int start_pos, int end_pos,
 
 
 PreParserIdentifier PreParserTraits::GetSymbol(Scanner* scanner) {
-  if (scanner->current_token() == Token::FUTURE_RESERVED_WORD) {
-    return PreParserIdentifier::FutureReserved();
+  if (scanner->current_token() == Token::ENUM) {
+    return PreParserIdentifier::Enum();
+  } else if (scanner->current_token() == Token::AWAIT) {
+    return PreParserIdentifier::Await();
   } else if (scanner->current_token() ==
              Token::FUTURE_STRICT_RESERVED_WORD) {
     return PreParserIdentifier::FutureStrictReserved();
@@ -694,7 +696,7 @@ PreParser::Statement PreParser::ParseExpressionOrLabelledStatement(bool* ok) {
   if (starts_with_identifier && expr.IsIdentifier() && peek() == Token::COLON) {
     // Expression is a single identifier, and not, e.g., a parenthesized
     // identifier.
-    DCHECK(!expr.AsIdentifier().IsFutureReserved());
+    DCHECK(!expr.AsIdentifier().IsEnum());

[mike3, 2016/02/24 16:26:25]

This check is equivalent to the previously-existing assertion. I haven't
extended it to include considerations for `await` because I don't think the
PreParser is able to determine whether it is parsing a module or not. That
information is provided when the Parser's `parse` method is invoked.

[adamk, 2016/02/24 19:13:25]

I think this means you need to add code to pass the parsing_module_ bit to
PreParseLazyFunction(), which is how the PreParser is invoked from
Parser::ParseLazyFunctionBodyWithPreParser.

I'll think about the right way to design a test case to cover that particular
behavior; it may not be possible at the moment. We never parse the top level of
a module with the PreParser.

     DCHECK(is_sloppy(language_mode()) ||
            !IsFutureStrictReserved(expr.AsIdentifier()));
     Consume(Token::COLON);