This commit adds a check of "process.title" to detect Node.js.

The web app bundler Parcel sets "process" to an empty object. This
incorrectly got detected as Node.js, even though the script was
running in a browser.

Fixes #28364.

Change-Id: Iecac7f8fc3cc4ac7ddb42dd43c5385681a3282de
Reviewed-on: https://go-review.googlesource.com/c/144658Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>