[stubs] Unify (and optimize) implementation of ToObject.

src/ppc/interface-descriptors-ppc.cc

Index: src/ppc/interface-descriptors-ppc.cc
diff --git a/src/ppc/interface-descriptors-ppc.cc b/src/ppc/interface-descriptors-ppc.cc
index c59fc56d248ad99a672cb3dc53c691bc19080d6d..8b605111c3d0e993c33f9a0c3f550f998336bc63 100644
--- a/src/ppc/interface-descriptors-ppc.cc
+++ b/src/ppc/interface-descriptors-ppc.cc
@@ -95,6 +95,10 @@ void ToNumberDescriptor::InitializePlatformSpecific(
 }
 
 
+// static
+const Register ToObjectDescriptor::ReceiverRegister() { return r3; }
+
+
 void NumberToStringDescriptor::InitializePlatformSpecific(
     CallInterfaceDescriptorData* data) {
   Register registers[] = {r3};