harmony-scoping: Allow 'const' iteration variables in strict mode.

src/preparser.cc

Index: src/preparser.cc
diff --git a/src/preparser.cc b/src/preparser.cc
index 987900a20d5844ebfef3e17d93fcd4c43f9503ea..316f129cc12bda987fc9e174319d68f0f36b307d 100644
--- a/src/preparser.cc
+++ b/src/preparser.cc
@@ -409,6 +409,7 @@ PreParser::Statement PreParser::ParseVariableDeclarations(
   // ConstBinding ::
   //   BindingPattern '=' AssignmentExpression
   bool require_initializer = false;
+  bool is_strict_const = false;
   if (peek() == Token::VAR) {
     Consume(Token::VAR);
   } else if (peek() == Token::CONST) {
@@ -430,7 +431,8 @@ PreParser::Statement PreParser::ParseVariableDeclarations(
           *ok = false;
           return Statement::Default();
         }
-        require_initializer = true;
+        is_strict_const = true;
+        require_initializer = var_context != kForStatement;
       } else {
         Scanner::Location location = scanner()->peek_location();
         ReportMessageAt(location, "strict_const");
@@ -460,7 +462,9 @@ PreParser::Statement PreParser::ParseVariableDeclarations(
     if (nvars > 0) Consume(Token::COMMA);
     ParseIdentifier(kDontAllowEvalOrArguments, CHECK_OK);
     nvars++;
-    if (peek() == Token::ASSIGN || require_initializer) {
+    if (peek() == Token::ASSIGN || require_initializer ||
+        // require initializers for multiple consts.
+        (is_strict_const && peek() == Token::COMMA)) {
       Expect(Token::ASSIGN, CHECK_OK);
       ParseAssignmentExpression(var_context != kForStatement, CHECK_OK);
       if (decl_props != NULL) *decl_props = kHasInitializers;
@@ -678,13 +682,14 @@ PreParser::Statement PreParser::ParseForStatement(bool* ok) {
   if (peek() != Token::SEMICOLON) {
     if (peek() == Token::VAR || peek() == Token::CONST ||
         (peek() == Token::LET && strict_mode() == STRICT)) {
-      bool is_let = peek() == Token::LET;
+      bool is_lexical = peek() == Token::LET ||
+                        (peek() == Token::CONST && strict_mode() == STRICT);
       int decl_count;
       VariableDeclarationProperties decl_props = kHasNoInitializers;
       ParseVariableDeclarations(
           kForStatement, &decl_props, &decl_count, CHECK_OK);
       bool has_initializers = decl_props == kHasInitializers;
-      bool accept_IN = decl_count == 1 && !(is_let && has_initializers);
+      bool accept_IN = decl_count == 1 && !(is_lexical && has_initializers);
       bool accept_OF = !has_initializers;
       if (accept_IN && CheckInOrOf(accept_OF)) {
         ParseExpression(true, CHECK_OK);