Sloppy-mode let parsing

src/parser.cc

Index: src/parser.cc
diff --git a/src/parser.cc b/src/parser.cc
index e53352d26c1d459dd732567c55b18373897ac7ee..a7affbae5f0b4072cde8ef618cc162df48b6215f 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -1391,7 +1391,7 @@ Statement* Parser::ParseStatementListItem(bool* ok) {
     case Token::VAR:
       return ParseVariableStatement(kStatementListItem, NULL, ok);
     case Token::LET:
-      if (allow_let()) {
+      if (IsLetKeyword()) {
         return ParseVariableStatement(kStatementListItem, NULL, ok);
       }
       break;
@@ -2638,9 +2638,6 @@ Statement* Parser::ParseExpressionOrLabelledStatement(
       }
       break;
 
-    // TODO(arv): Handle `let [`
-    // https://code.google.com/p/v8/issues/detail?id=3847
-
     default:
       break;
   }
@@ -3515,7 +3512,7 @@ Statement* Parser::ParseForStatement(ZoneList<const AstRawString*>* labels,
   DeclarationParsingResult parsing_result;
   if (peek() != Token::SEMICOLON) {
     if (peek() == Token::VAR || (peek() == Token::CONST && allow_const()) ||
-        (peek() == Token::LET && allow_let())) {
+        (peek() == Token::LET && IsLetKeyword())) {
       ParseVariableDeclarations(kForStatement, &parsing_result, CHECK_OK);
       is_const = parsing_result.descriptor.mode == CONST;