Creating a js object with `Object.create(null)` produces an empty
js object with no prototype. Calling methods attached to these
objects would result in a NPE since we assumed all objects would
have a valid `.__proto__`.
Discovered the error in some benchmark code. Created a new test
with the same patterns.
Change-Id: I1fd38893b0c90315b338c3b6a1b4981be1d64065
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/156582
Commit-Queue: Nicholas Shahan <nshahan@google.com>
Reviewed-by: Mark Zhou <markzipan@google.com>
Nicholas Shahan