fix/460-track-browser-dom-ts

[MasterKale]

This PR starts tracking packages/typescript-types/dom.ts so that the import from "./dom.ts" in index.ts can resolve in Deno projects.

And this file doesn't often need to be codegen'd, only when I update the version of TypeScript specified in the root package.json, so I won't codegen dom.ts on builds anymore.

To confirm the fix I ran the following and confirmed the deno vendor command succeeded:

$> cd scratchenv/460-deno-types-dom-ts
$> deno vendor ../../deno/server.ts --no-config --force
Vendored 101 modules into vendor/ directory.

To use vendored modules, specify the `--import-map vendor/import_map.json` flag when invoking Deno subcommands or add an `"importMap": "<path_to_vendored_import_map>"` entry to a deno.json file.

Fixes #460.