Eliminate redundant descriptor ElementTransitionAndStoreDescriptor.

src/ia32/interface-descriptors-ia32.cc

Index: src/ia32/interface-descriptors-ia32.cc
diff --git a/src/ia32/interface-descriptors-ia32.cc b/src/ia32/interface-descriptors-ia32.cc
index fda6de1de6fd7b25fd8ad7a16798343f5dbcb7f4..e1138b959de063cbaef3cb4334d114b10a5be974 100644
--- a/src/ia32/interface-descriptors-ia32.cc
+++ b/src/ia32/interface-descriptors-ia32.cc
@@ -46,11 +46,6 @@ const Register StoreGlobalViaContextDescriptor::NameRegister() { return ecx; }
 const Register StoreGlobalViaContextDescriptor::ValueRegister() { return eax; }
 
 
-const Register ElementTransitionAndStoreDescriptor::MapRegister() {
-  return ebx;
-}
-
-
 const Register InstanceofDescriptor::left() { return eax; }
 const Register InstanceofDescriptor::right() { return edx; }