Replaces many loops of the form:
```js
for (let i = 0; i < elements.length; ++i) {
const i = elements[i];
...
}
```
with:
```js
for (const element of elements) {
...
}
```
Mix of a horrible regex based find/replace and manual touch ups
Continue moving emmet extension to strict mode. This change does the following:
- Remove jsdoc types. These are unused in ts files and can easily get out of date
- Annotate when something can return undefined
- Add null checks for when something can be undefined
- Add explicit types when something can be any
