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

src/interface-descriptors.h

Index: src/interface-descriptors.h
diff --git a/src/interface-descriptors.h b/src/interface-descriptors.h
index c5e104fba833372a40313ef309858a14e4d3f258..a016797623a4331fdec2acab881d2899898f84ba 100644
--- a/src/interface-descriptors.h
+++ b/src/interface-descriptors.h
@@ -24,6 +24,7 @@ class PlatformInterfaceDescriptor;
   V(FastNewClosure)                           \
   V(FastNewContext)                           \
   V(ToNumber)                                 \
+  V(ToObject)                                 \
   V(NumberToString)                           \
   V(Typeof)                                   \
   V(FastCloneShallowArray)                    \
@@ -339,6 +340,16 @@ class ToNumberDescriptor : public CallInterfaceDescriptor {
 };
 
 
+class ToObjectDescriptor : public CallInterfaceDescriptor {
+ public:
+  enum ParameterIndices { kReceiverIndex };
+
+  DECLARE_DESCRIPTOR(ToObjectDescriptor, CallInterfaceDescriptor)
+
+  static const Register ReceiverRegister();
+};
+
+
 class NumberToStringDescriptor : public CallInterfaceDescriptor {
  public:
   DECLARE_DESCRIPTOR(NumberToStringDescriptor, CallInterfaceDescriptor)