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

src/x64/interface-descriptors-x64.cc

Index: src/x64/interface-descriptors-x64.cc
diff --git a/src/x64/interface-descriptors-x64.cc b/src/x64/interface-descriptors-x64.cc
index da5e506b2a4c83b88e638f555052c90d45f8986c..3bc6cd212ba377599c5ae14f20c3dc905be4a655 100644
--- a/src/x64/interface-descriptors-x64.cc
+++ b/src/x64/interface-descriptors-x64.cc
@@ -103,6 +103,14 @@ void ToNumberDescriptor::InitializePlatformSpecific(
 }
 
 
+void ToObjectDescriptor::InitializePlatformSpecific(
+    CallInterfaceDescriptorData* data) {
+  // ToObjectStub invokes a function, and therefore needs a context.
+  Register registers[] = {rax};
+  data->InitializePlatformSpecific(arraysize(registers), registers);
+}
+
+
 void NumberToStringDescriptor::InitializePlatformSpecific(
     CallInterfaceDescriptorData* data) {
   Register registers[] = {rax};