Remove unused HIsNumberAndBranch instruction.

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 6bb8bbefd98257af39c23d66d3a477da2d83d741..ad3b854ce5a73efa3a700209d66822cec0def589 100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -1921,12 +1921,6 @@ LInstruction* LChunkBuilder::DoCheckSmi(HCheckSmi* instr) {
 }
 
 
-LInstruction* LChunkBuilder::DoIsNumberAndBranch(HIsNumberAndBranch* instr) {
-  return new(zone())
-    LIsNumberAndBranch(UseRegisterOrConstantAtStart(instr->value()));
-}
-
-
 LInstruction* LChunkBuilder::DoCheckInstanceType(HCheckInstanceType* instr) {
   LOperand* value = UseRegisterAtStart(instr->value());
   LInstruction* result = new(zone()) LCheckInstanceType(value);