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 8a97b2d7852ee628af7ae2da45d9acc53981f1ee..c42aebc411b80f9b865f7bdf9b372b567c39de4b 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -228,6 +228,17 @@ MaybeHandle<Object> Object::ToLength(Isolate* isolate, Handle<Object> input) {
   return isolate->factory()->NewNumber(len);
 }
 
+// static
+MaybeHandle<Object> Object::ToIndex(Isolate* isolate, Handle<Object> input) {
+  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;
+  if (len < 0.0 || len > kMaxSafeInteger) {
+    THROW_NEW_ERROR(isolate, NewRangeError(MessageTemplate::kInvalidIndex),
+                    Object);
+  }
+  return isolate->factory()->NewNumber(len);
+}
 
 bool Object::BooleanValue() {
   if (IsSmi()) return Smi::cast(this)->value() != 0;