License fields not populated when using web ide

Summary

Some licenses, and perhaps other templates, support prefilling fields like [year] and [fullname]. When using the old file template interface these work, but in the web ide they do not.

Steps to reproduce

1. In the web IDE create a LICENSE and use the MIT license template

What is the current bug behavior?

The license created looks like:

MIT License

Copyright (c) [year] [fullname]

Permission is hereby granted, free of charge, to any person obtaining a copy
...

What is the expected correct behavior?

MIT License

Copyright (c) 2018 James Ramsay

Permission is hereby granted, free of charge, to any person obtaining a copy
...

Output of checks

This bug happens on GitLab.com

Links / references

https://gitlab.com/gitlab-org/gitlab-ce/issues/47947