fix(autocomplete): two chips added on enter w/ IE11

[Splaktar]

PR Checklist

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• The commit message follows our guidelines
• Tests for the changes have been added or this is not a bug fix / enhancement
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PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Enhancement
[ ] Documentation content changes
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

Pressing enter to add a chip can cause two chips to be created in certain cases on IE11.

Issue Number:
Fixes #10640. Closes #10667.

What is the new behavior?

Pressing enter to add a chip no longer can cause two chips to be created in certain cases on IE11.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

Many thanks to @RudolfFrederiksen for helping debug this and come up with a solution.