Revert of Remove ExternalArray, derived types, and element kinds

src/x64/lithium-x64.h

Index: src/x64/lithium-x64.h
diff --git a/src/x64/lithium-x64.h b/src/x64/lithium-x64.h
index 06158d47976d9eb3c21a8bbb2ced543a6f7bd697..95d56beb2c62bc499f49746ef6b2bb1a7bff9c9a 100644
--- a/src/x64/lithium-x64.h
+++ b/src/x64/lithium-x64.h
@@ -1617,8 +1617,12 @@
   // an index cannot fold the scale operation into a load and need an extra
   // temp register to do the work.
   return SmiValuesAre31Bits() && key_representation.IsSmi() &&
-         (elements_kind == UINT8_ELEMENTS || elements_kind == INT8_ELEMENTS ||
-          elements_kind == UINT8_CLAMPED_ELEMENTS);
+      (elements_kind == EXTERNAL_INT8_ELEMENTS ||
+       elements_kind == EXTERNAL_UINT8_ELEMENTS ||
+       elements_kind == EXTERNAL_UINT8_CLAMPED_ELEMENTS ||
+       elements_kind == UINT8_ELEMENTS ||
+       elements_kind == INT8_ELEMENTS ||
+       elements_kind == UINT8_CLAMPED_ELEMENTS);
 }
 
 
@@ -1632,8 +1636,14 @@
   DECLARE_CONCRETE_INSTRUCTION(LoadKeyed, "load-keyed")
   DECLARE_HYDROGEN_ACCESSOR(LoadKeyed)
 
+  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]; }
@@ -2225,8 +2235,12 @@
     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]; }