Cleanup type checking in "--compat" mode

[bartlomieju]

Currently in --compat mode during type-checking std/node/global.ts is unconditionally added to the roots of module graph created:

deno/cli/proc_state.rs

Lines 302 to 310 in 71da814

	// TODO(bartlomieju): this is very make-shift, is there an existing API
	// that we could include it like with "maybe_imports"?
	let roots = if self.flags.compat {
	let mut r = vec![compat::GLOBAL_URL.clone()];
	r.extend(roots);
	r
	} else {
	roots
	};