Remove HFixedArrayBaseLength instruction and replace with regular HLoadNamedField.

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index 9c2373a0aab73af6983fde5fe94e945d91298abd..95a44f038427f1145aa47563af3f023f0c1face2 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -1718,13 +1718,6 @@ LInstruction* LChunkBuilder::DoClassOfTestAndBranch(
 }
 
 
-LInstruction* LChunkBuilder::DoFixedArrayBaseLength(
-    HFixedArrayBaseLength* instr) {
-  LOperand* array = UseRegisterAtStart(instr->value());
-  return DefineAsRegister(new(zone()) LFixedArrayBaseLength(array));
-}
-
-
 LInstruction* LChunkBuilder::DoMapEnumLength(HMapEnumLength* instr) {
   LOperand* map = UseRegisterAtStart(instr->value());
   return DefineAsRegister(new(zone()) LMapEnumLength(map));