Fast string construct stub (ia32 only for now).

src/x64/builtins-x64.cc

Index: src/x64/builtins-x64.cc
diff --git a/src/x64/builtins-x64.cc b/src/x64/builtins-x64.cc
index e5d9d04b4ba945e5a972ac7e845148965bc3fd5b..caf375092c139b273d65dcaa3f3b33d99a92d450 100644
--- a/src/x64/builtins-x64.cc
+++ b/src/x64/builtins-x64.cc
@@ -875,6 +875,13 @@ void Builtins::Generate_ArrayConstructCode(MacroAssembler* masm) {
 }
 
 
+void Builtins::Generate_StringConstructCode(MacroAssembler* masm) {
+  // TODO(bug): implement custom construct stub.
+  // Generate a copy of the generic stub for now.
+  Generate_JSConstructStubGeneric(masm);
+}
+
+
 void Builtins::Generate_JSConstructCall(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- rax: number of arguments