Remove HFixedArrayBaseLength instruction and replace with regular HLoadNamedField.

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index c97475a94821de92651c6c16700c9fe57f2ab92b..de43f86a3d2b6e154d7535d5719b0114a0149531 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -1553,13 +1553,6 @@ void LCodeGen::DoConstantT(LConstantT* instr) {
 }
 
 
-void LCodeGen::DoFixedArrayBaseLength(LFixedArrayBaseLength* instr) {
-  Register result = ToRegister(instr->result());
-  Register array = ToRegister(instr->value());
-  __ movq(result, FieldOperand(array, FixedArrayBase::kLengthOffset));
-}
-
-
 void LCodeGen::DoMapEnumLength(LMapEnumLength* instr) {
   Register result = ToRegister(instr->result());
   Register map = ToRegister(instr->value());