Optimization: a Stack/Heap approach

Instead of

```css
body {
color: red
}
```

producing

```js
[
[RULE_START, 1],
[SELECTOR, 'body'],
[PROPERTY, 'color'],
[VALUE, 'red']
[RULE_END]
]
```

It could instead produce

```js
HEAP = ['body', 'color', 'red']

[
RULE_START, 0,
SELECTOR, 0,
PROPERTY, 1,
VALUE, 2,
RULE_END, 2
]
```

Where the ints `0,1,2` are memory addresses for the corresponding values in the `HEAP`.

This way you can use a flat `Uint32Array` typed array for maximum throughput on performance.

No files, tests, or implementation entry points are named. Start by reviewing the proposed HEAP and flat Uint32Array representations and the 50-comment discussion; completion requires an agreed design and a documented or implemented format that addresses the stated throughput goal.

Written by the indexing model from the issue text.