Revert of Remove ExternalArray, derived types, and element kinds

src/arm/lithium-arm.h

Index: src/arm/lithium-arm.h
diff --git a/src/arm/lithium-arm.h b/src/arm/lithium-arm.h
index 7f2ab11b2dd4f71ace90797a863714012f88f296..4eeca332ec1e834d77188855f9d4862c09b9d884 100644
--- a/src/arm/lithium-arm.h
+++ b/src/arm/lithium-arm.h
@@ -1647,8 +1647,14 @@
   ElementsKind elements_kind() const {
     return hydrogen()->elements_kind();
   }
+  bool is_external() const {
+    return hydrogen()->is_external();
+  }
   bool is_fixed_typed_array() const {
     return hydrogen()->is_fixed_typed_array();
+  }
+  bool is_typed_elements() const {
+    return is_external() || is_fixed_typed_array();
   }
 
   DECLARE_CONCRETE_INSTRUCTION(LoadKeyed, "load-keyed")
@@ -2249,8 +2255,12 @@
     inputs_[2] = value;
   }
 
+  bool is_external() const { return hydrogen()->is_external(); }
   bool is_fixed_typed_array() const {
     return hydrogen()->is_fixed_typed_array();
+  }
+  bool is_typed_elements() const {
+    return is_external() || is_fixed_typed_array();
   }
   LOperand* elements() { return inputs_[0]; }
   LOperand* key() { return inputs_[1]; }