Bundling does not inline all symbols into a single scope, tree shaking does. I was one of the people implementing tree shaking in the first Parcel bundler. https://github.com/parcel-bundler/parcel/pull/1135
Scope hoisting is the technique used there (it's in the title of your link) to simplify tree shaking a.k.a dead code elimination. Also yeah it's unlikely to be what's happening in that bug due to Google using Closure compiler.
