Make let variables fresh in each iteration of a for-loop.

src/parser.h

Index: src/parser.h
diff --git a/src/parser.h b/src/parser.h
index 10be1707ea7d03e95bbb6f1c1b2fc954c6bb2ea5..affff80156f385cfe814bfd7066b029a5f875860 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -718,6 +718,12 @@ class Parser : public ParserBase<ParserTraits> {
                                   Expression* each,
                                   Expression* subject,
                                   Statement* body);
+  Statement* DesugarLetBindingsInForStatement(

[rossberg, 2014/05/22 12:55:44]

Nit: DesugarLexicalDeclarationInForStatement, since in fact, it might also be
const (or others).

[ulan, 2014/05/23 14:29:03]

As discussed offline, const and others are not handled here.

+      Scope* inner_scope, ZoneStringList* names, ForStatement* loop,
+      Statement* init, Expression* cond, Statement* next, bool* ok);
+  Statement* Assign(Token::Value op, VariableProxy* dst, Expression* src,

[rossberg, 2014/05/22 12:55:44]

I am not sure if it's actually worth introducing these extra functions. But if
you do, they should probably be named NewAssignmentStatement and NewTemporary
for consistency with other such helpers. Also, please then update other places
in the parser calling NewAssignmentExpression and Scope::NewTemporary to use
them consistently.

[ulan, 2014/05/23 14:29:03]

Done. Inlined the functions to be consistent.

+                    int pos = RelocInfo::kNoPosition);
+  Variable* Temporary(Handle<String> name);
 
   FunctionLiteral* ParseFunctionLiteral(
       Handle<String> name,