[compiler] Drop the CompareNilIC.

src/mips/interface-descriptors-mips.cc

Index: src/mips/interface-descriptors-mips.cc
diff --git a/src/mips/interface-descriptors-mips.cc b/src/mips/interface-descriptors-mips.cc
index fdb43f325cab342877aefd6e4de6ac3653a5de0c..f8b2876313a4496f8f813778ca852f1ecdec98a1 100644
--- a/src/mips/interface-descriptors-mips.cc
+++ b/src/mips/interface-descriptors-mips.cc
@@ -318,13 +318,6 @@ void CompareDescriptor::InitializePlatformSpecific(
 }
 
 
-void CompareNilDescriptor::InitializePlatformSpecific(
-    CallInterfaceDescriptorData* data) {
-  Register registers[] = {a0};
-  data->InitializePlatformSpecific(arraysize(registers), registers, NULL);
-}
-
-
 void ToBooleanDescriptor::InitializePlatformSpecific(
     CallInterfaceDescriptorData* data) {
   Register registers[] = {a0};