Remove HIsNilAndBranch (it's now unused)

src/hydrogen-instructions.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1236 matching lines @@
   stream->Add(")");
 }
 
 
 void HUnaryControlInstruction::PrintDataTo(StringStream* stream) {
   value()->PrintNameTo(stream);
   HControlInstruction::PrintDataTo(stream);
 }
 
 
-void HIsNilAndBranch::PrintDataTo(StringStream* stream) {
-  value()->PrintNameTo(stream);
-  stream->Add(kind() == kStrictEquality ? " === " : " == ");
-  stream->Add(nil() == kNullValue ? "null" : "undefined");
-  HControlInstruction::PrintDataTo(stream);
-}
-
-
 void HReturn::PrintDataTo(StringStream* stream) {
   value()->PrintNameTo(stream);
   stream->Add(" (pop ");
   parameter_count()->PrintNameTo(stream);
   stream->Add(" values)");
 }
 
 
 Representation HBranch::observed_input_representation(int index) {
   static const ToBooleanStub::Types tagged_types(
@@ skipping 2390 matching lines @@
 
 
 void HCheckFunction::Verify() {
   HInstruction::Verify();
   ASSERT(HasNoUses());
 }
 
 #endif
 
 } }  // namespace v8::internal