arrange to create prototypes for generators

src/x64/code-stubs-x64.cc

Index: src/x64/code-stubs-x64.cc
diff --git a/src/x64/code-stubs-x64.cc b/src/x64/code-stubs-x64.cc
index fffd37f519db9c9dcb19fb44d5640de8e39093e9..7513d13ebe4ce785e622f274aff7021a68d11ef8 100644
--- a/src/x64/code-stubs-x64.cc
+++ b/src/x64/code-stubs-x64.cc
@@ -158,9 +158,13 @@ void FastNewClosureStub::Generate(MacroAssembler* masm) {
   // Get the function info from the stack.
   __ movq(rdx, Operand(rsp, 1 * kPointerSize));
 
-  int map_index = (language_mode_ == CLASSIC_MODE)
-      ? Context::FUNCTION_MAP_INDEX
-      : Context::STRICT_MODE_FUNCTION_MAP_INDEX;
+  int map_index = is_generator_
+      ? ((language_mode_ == CLASSIC_MODE)
+         ? Context::GENERATOR_FUNCTION_MAP_INDEX
+         : Context::STRICT_MODE_GENERATOR_FUNCTION_MAP_INDEX)
+      : ((language_mode_ == CLASSIC_MODE)
+         ? Context::FUNCTION_MAP_INDEX
+         : Context::STRICT_MODE_FUNCTION_MAP_INDEX);
 
   // Compute the function map in the current native context and set that
   // as the map of the allocated object.