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

src/ppc/lithium-codegen-ppc.cc

Index: src/ppc/lithium-codegen-ppc.cc
diff --git a/src/ppc/lithium-codegen-ppc.cc b/src/ppc/lithium-codegen-ppc.cc
index 50dcd191274286b61c63b4fefc2831438e719f38..fb2b8238229e97f572788880764943e9807be1f5 100644
--- a/src/ppc/lithium-codegen-ppc.cc
+++ b/src/ppc/lithium-codegen-ppc.cc
@@ -118,7 +118,7 @@ bool LCodeGen::GeneratePrologue() {
     // Sloppy mode functions and builtins need to replace the receiver with the
     // global proxy when called as functions (without an explicit receiver
     // object).
-    if (graph()->this_has_uses() && is_sloppy(info_->language_mode()) &&
+    if (is_sloppy(info_->language_mode()) && info()->MayUseThis() &&
         !info_->is_native()) {
       Label ok;
       int receiver_offset = info_->scope()->num_parameters() * kPointerSize;