Since typedarrays are integer indexed exotic objects, we don't need to
check if prototypes of a typedarray have elements or not.

https://tc39.github.io/ecma262/#sec-integer-indexed-exotic-objects-get-p-receiver

BUG=699020

Review-Url: https://codereview.chromium.org/2744103002
Cr-Commit-Position: refs/heads/master@{#43738}