Generate TypedArrayInitialize builtin in hydrogen.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index c77c2ebf0e495a134172b2da370b19eebfdfb6cc..ffa3c5ab7e39f4cb6e98a3ba8278bf819933b73b 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -4755,8 +4755,9 @@ class HAdd V8_FINAL : public HArithmeticBinaryOperation {
 
   // Add is only commutative if two integer values are added and not if two
   // tagged values are added (because it might be a String concatenation).
+  // We also do not commute (pointer + offset).
   virtual bool IsCommutative() const V8_OVERRIDE {
-    return !representation().IsTagged();
+    return !representation().IsTagged() && !representation().IsExternal();
   }
 
   virtual HValue* EnsureAndPropagateNotMinusZero(
@@ -4792,6 +4793,10 @@ class HAdd V8_FINAL : public HArithmeticBinaryOperation {
     }
   }
 
+  virtual Representation RepresentationFromInputs() V8_OVERRIDE;
+
+  virtual Representation RequiredInputRepresentation(int index) V8_OVERRIDE;
+
   DECLARE_CONCRETE_INSTRUCTION(Add)
 
  protected:
@@ -6509,6 +6514,8 @@ class HStoreNamedField V8_FINAL : public HTemplateInstruction<3> {
       } else if (field_representation().IsDouble() ||
                  field_representation().IsSmi()) {
         return field_representation();
+      } else if (field_representation().IsExternal()) {
+        return Representation::External();
       }
     }
     return Representation::Tagged();