Amend DataView, ArrayBuffer, and TypedArray methods to use ToIndex.

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 2da837e8ab82022e55294f722d9d5d37f57c73ce..35f1e47155f55cb815c93e1a60ec1ad32ab2875e 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -228,6 +228,18 @@ MaybeHandle<Object> Object::ToLength(Isolate* isolate, Handle<Object> input) {
   return isolate->factory()->NewNumber(len);
 }
 
+// static
+MaybeHandle<Object> Object::ToIndex(Isolate* isolate, Handle<Object> input,
+                                    MessageTemplate::Template error_index) {
+  if (input->IsUndefined(isolate)) return isolate->factory()->NewNumber(0.0);
+  ASSIGN_RETURN_ON_EXCEPTION(isolate, input, ToNumber(input), Object);
+  double len = DoubleToInteger(input->Number()) + 0.0;
+  auto js_len = isolate->factory()->NewNumber(len);
+  if (len < 0.0 || len > kMaxSafeInteger) {
+    THROW_NEW_ERROR(isolate, NewRangeError(error_index, js_len), Object);
+  }
+  return js_len;
+}
 
 bool Object::BooleanValue() {
   if (IsSmi()) return Smi::cast(this)->value() != 0;