[crankshaft] Remove the useless HMapEnumLength instruction.

src/crankshaft/x64/lithium-codegen-x64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/crankshaft/x64/lithium-codegen-x64.h"
 
 #include "src/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 1642 matching lines @@
 }
 
 
 void LCodeGen::DoConstantT(LConstantT* instr) {
   Handle<Object> object = instr->value(isolate());
   AllowDeferredHandleDereference smi_check;
   __ Move(ToRegister(instr->result()), object);
 }
 
 
-void LCodeGen::DoMapEnumLength(LMapEnumLength* instr) {
-  Register result = ToRegister(instr->result());
-  Register map = ToRegister(instr->value());
-  __ EnumLength(result, map);
-}
-
-
 Operand LCodeGen::BuildSeqStringOperand(Register string,
                                         LOperand* index,
                                         String::Encoding encoding) {
   if (index->IsConstantOperand()) {
     int offset = ToInteger32(LConstantOperand::cast(index));
     if (encoding == String::TWO_BYTE_ENCODING) {
       offset *= kUC16Size;
     }
     STATIC_ASSERT(kCharSize == 1);
     return FieldOperand(string, SeqString::kHeaderSize + offset);
@@ skipping 3969 matching lines @@
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64