Adds support for the following HTML elements to the HTML Processor:
- LI, OL, UL.
- DD, DL, DT.
Previously, these elements were not supported and the HTML Processor would bail when encountering them.
With this patch it will proceed to parse an HTML document when encountering those tags as long as other normal conditions don't cause it to bail (such as complicated format reconstruction).
Props audrasjb, jonsurrell, bernhard-reiter.
Fixes#60215.
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