Ember

Describe the bug
In Firefox, the zoom feature uses transform styles (see storybookjs/storybook#12845) - unfortunately this breaks positioning on elements that require position: fixed when in the "Docs" view.

Normally a position: fixed element's position would correspond to the viewport but in Firefox it corresponds to the element with the transform style.

ember-cli/ember-cli#8209 skipped some of our smoke tests that were failing for an unknown reason on TravisCI. We should try to fix and unskip them to increase confidence in our test suite.

Relevant conversation here: hjdivad/ember-m3#807

We seem to miss test coverage for some arguments supported by <BsModal>. I only had a very brief look but it seems to miss tests for at least the following arguments:

• @size
• @centered
• @scrollable