Overlapping multi chars highlighting

[atomiks]

Two separate issues:

1. There's no way to add "sub" highlights. Both getStringLength and get should be separately highlighted.

```js /getStringLength/ /get/
const getStringLength = str => str.length;
```

2. Chars can inherit a range incorrectly, even when not encompassed by a different chars highlight (such as with the above overlapping scenario).

```js /get/1 /Length/
const getStringLength = str => str.length;
const getStringLength = str => str.length;
```

The first get is correctly highlighted, but Length incorrectly inherits the range from get because it's within the same textContent of the node (getStringLength) and also only ends up highlighting the first Length.

[juji]

This is also weird:

Also this one: