chasefleming/elem-go

AI Summary: Add support for the HTML5 `<track>` element to the `elem-go` library, including adding a new element function, a corresponding test case, and any necessary attributes to the `attrs` package. The `<track>` element has no end tag and therefore no children.

AI Summary: Add support for the HTML `<wbr>` element to the `elem-go` library, including adding a new element function in `elements.go` and a corresponding test case in `elements_test.go`. The `<wbr>` element is a word break opportunity element and has no end tag or children.