Error checking for length parameter of external array constructors in shell

src/d8.h

Index: src/d8.h
diff --git a/src/d8.h b/src/d8.h
index e62ce3803642a17e9fcc339acbd0bb77dc52e2e4..1071c9a0b999e912fb535b0ed3575bd1451377b2 100644
--- a/src/d8.h
+++ b/src/d8.h
@@ -219,7 +219,7 @@ class Shell: public i::AllStatic {
   static Counter* GetCounter(const char* name, bool is_histogram);
   static Handle<Value> CreateExternalArray(const Arguments& args,
                                            ExternalArrayType type,
-                                           int element_size);
+                                           size_t element_size);
   static void ExternalArrayWeakCallback(Persistent<Value> object, void* data);
 };