Remove HIsNilAndBranch (it's now unused)

src/mips/lithium-mips.cc

Index: src/mips/lithium-mips.cc
diff --git a/src/mips/lithium-mips.cc b/src/mips/lithium-mips.cc
index b5c47ef859317aee52b457b00b55ceeef6fee598..719acb3b39e3f93ebe3139efc841cf5317d6cdaf 100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -217,15 +217,6 @@ void LCmpIDAndBranch::PrintDataTo(StringStream* stream) {
 }
 
 
-void LIsNilAndBranch::PrintDataTo(StringStream* stream) {
-  stream->Add("if ");
-  value()->PrintTo(stream);
-  stream->Add(kind() == kStrictEquality ? " === " : " == ");
-  stream->Add(nil() == kNullValue ? "null" : "undefined");
-  stream->Add(" then B%d else B%d", true_block_id(), false_block_id());
-}
-
-
 void LIsObjectAndBranch::PrintDataTo(StringStream* stream) {
   stream->Add("if is_object(");
   value()->PrintTo(stream);
@@ -1592,12 +1583,6 @@ LInstruction* LChunkBuilder::DoCompareConstantEqAndBranch(
 }
 
 
-LInstruction* LChunkBuilder::DoIsNilAndBranch(HIsNilAndBranch* instr) {
-  ASSERT(instr->value()->representation().IsTagged());
-  return new(zone()) LIsNilAndBranch(UseRegisterAtStart(instr->value()));
-}
-
-
 LInstruction* LChunkBuilder::DoIsObjectAndBranch(HIsObjectAndBranch* instr) {
   ASSERT(instr->value()->representation().IsTagged());
   LOperand* temp = TempRegister();