[crankshaft] Remove the useless HMapEnumLength instruction.

src/crankshaft/arm/lithium-codegen-arm.cc

Index: src/crankshaft/arm/lithium-codegen-arm.cc
diff --git a/src/crankshaft/arm/lithium-codegen-arm.cc b/src/crankshaft/arm/lithium-codegen-arm.cc
index 8ded96df83cf2819c8446de63d0b4ef770c57eb5..5646410ccc5801a2159b5e1b75727ea197f8af28 100644
--- a/src/crankshaft/arm/lithium-codegen-arm.cc
+++ b/src/crankshaft/arm/lithium-codegen-arm.cc
@@ -1803,13 +1803,6 @@ void LCodeGen::DoConstantT(LConstantT* instr) {
 }
 
 
-void LCodeGen::DoMapEnumLength(LMapEnumLength* instr) {
-  Register result = ToRegister(instr->result());
-  Register map = ToRegister(instr->value());
-  __ EnumLength(result, map);
-}
-
-
 MemOperand LCodeGen::BuildSeqStringOperand(Register string,
                                            LOperand* index,
                                            String::Encoding encoding) {