add failing test for dynamic attributes on custom html tag

[yomed]

Description

Hi, this is not intended for merge, just to show an issue. Using dynamic attributes with custom html elements leads to the following error:

Error: Generating code for TemplateRoot node failed. 
Error: Error: Generating code for <custom-html-tag> tag failed.
Error: AssertionError [ERR_ASSERTION]: "name" should be a string

Checklist:

• My code follows the code style of this project.
• I have updated/added documentation affected by my changes.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

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[mlrawlings]

I'm going to close this as it's just been sitting and the test structure has changed since this PR was opened. We now have a way to merge failing test cases, so if this is still an issue and someone can open a PR with a failing test case we'll take another look.