Parse harmony let declarations.

src/parser.h

Index: src/parser.h
diff --git a/src/parser.h b/src/parser.h
index dd964cebd6627d0c5ef61d2ee4b06ba5e90a6ec8..377962e1edcc38cdea061efc4042efb03ffbd2e4 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -480,13 +480,15 @@ class Parser {
   // for failure at the call sites.
   void* ParseSourceElements(ZoneList<Statement*>* processor,
                             int end_token, bool* ok);
+  Statement* ParseSourceElement(ZoneStringList* labels, bool* ok);
   Statement* ParseStatement(ZoneStringList* labels, bool* ok);
   Statement* ParseFunctionDeclaration(bool* ok);
   Statement* ParseNativeDeclaration(bool* ok);
   Block* ParseBlock(ZoneStringList* labels, bool* ok);
   Block* ParseScopedBlock(ZoneStringList* labels, bool* ok);
-  Block* ParseVariableStatement(bool* ok);
-  Block* ParseVariableDeclarations(bool accept_IN,
+  Block* ParseVariableStatement(bool accept_LET, bool* ok);
+  Block* ParseVariableDeclarations(bool accept_LET,
+                                   bool accept_IN,
                                    Handle<String>* out,
                                    bool* ok);
   Statement* ParseExpressionOrLabelledStatement(ZoneStringList* labels,