Missing tests for many of the Webapi/Dom elements

[eschaefer]

I'm trying to add support for HTMLMediaElement and HTMLVideoElement and wondered what a canonical way of adding tests should look like. This made me notice that tests are actually missing for many of the elements in the Webapi/Dom. Just the first few that I noticed immediately:

• HTMLSelectElement
• HTMLTextAreaElement
• HTMLOptionElement

I'm guessing there are many more.

[TheSpyder]

The "tests" are not tests in the traditional sense, they exist to check that the generated JS output doesn't change unintentionally. However after a few incidents where the type changed unintentionally, I logged a task (#42) that describes how I'd like tests to be written to address that as well. Some time ago I started a branch where I began that work but then my personal life became busy and I haven't gone back to it since.

Help is certainly appreciated; you can either start with my branch or create a new one.