Add local alias for toString

[corvidism]

Set toString to Object.prototype.toString as the code implicitly expects, to avoid conflicts with mocked globals. (see issue #405).

[salesforce-cla]

Thanks for the contribution! Before we can merge this, we need @corvidism to sign the Salesforce Inc. Contributor License Agreement.

[salesforce-cla]

Thanks for the contribution! Before we can merge this, we need @inikulin @stash-sfdc to sign the Salesforce Inc. Contributor License Agreement.

[salesforce-cla]

Thanks for the contribution! Unfortunately we can't verify the commit author(s): Yevhen Lukomskyi <Y***@3***.com>. One possible solution is to add that email to your GitHub account. Alternatively you can change your commits to another email and force push the change. After getting your commits associated with your GitHub account, sign the Salesforce Inc. Contributor License Agreement and this Pull Request will be revalidated.

[colincasey]

@corvidism thanks for the PR! Now I just have to figure out how to backport this into the 4.1.x release since that's not something I've had to do with this project before but I'll try to get to it by the end of the week.

[corvidism]

Great! Thanks for the effort.

[colincasey]

Closing and reopening to see if it fixes the synk PR checks.