Unify internal and external typed arrays a bit

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 6f56c7639148282471bfd4ce0ebfeb3be9b6ce5e..e49e86024f29e1ced61783a8d16173703e612a50 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -6130,6 +6130,11 @@ class HObjectAccess final {
         JSArrayBuffer::kBitFieldOffset, Representation::Integer32());
   }
 
+  static HObjectAccess ForJSArrayBufferBitFieldSlot() {
+    return HObjectAccess::ForObservableJSObjectOffset(
+        JSArrayBuffer::kBitFieldSlot, Representation::Smi());
+  }
+
   static HObjectAccess ForExternalArrayExternalPointer() {
     return HObjectAccess::ForObservableJSObjectOffset(
         ExternalArray::kExternalPointerOffset, Representation::External());