Only swap undefined for the global object if necessary in the prologue

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index 94da774891d40872bfa5302e32a52e760bf41823..7f0f66d0e5f7d2686ec10f4c1aeb6ca5684faef8 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -114,7 +114,8 @@ void FullCodeGenerator::Generate() {
   // Sloppy mode functions and builtins need to replace the receiver with the
   // global proxy when called as functions (without an explicit receiver
   // object).
-  if (is_sloppy(info->language_mode()) && !info->is_native()) {
+  if (is_sloppy(info->language_mode()) && !info->is_native() &&
+      info->MayUseThis()) {
     Label ok;
     // +1 for return address.
     StackArgumentsAccessor args(rsp, info->scope()->num_parameters());