do not load Bootstrap in non-admin controller for non-bundle themes.

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| Refs tickets  | #2041
| License       | MIT
| Doc PR        | -

`{` needs to be on the next line. Also, you must not (IMO) add functions to the global namespace. If you really wanted to use an extra function, you could've used an anonymous function instead.