Use same algorithm in latY

[jingsam]

We projected latitude to Y in two places:

mapbox-gl-js/src/geo/transform.js

Lines 288 to 291 in cbe1cec

	latY(lat: number) {
	const y = 180 / Math.PI * Math.log(Math.tan(Math.PI / 4 + lat * Math.PI / 360));
	return (180 - y) * this.worldSize / 360;
	}

mapbox-gl-js/src/source/tile_bounds.js

Lines 40 to 44 in cbe1cec

	latY(lat: number, zoom: number) {
	const f = clamp(Math.sin(Math.PI / 180 * lat), -0.9999, 0.9999);
	const scale = Math.pow(2, zoom) / (2 * Math.PI);
	return Math.pow(2, zoom - 1) + 0.5 * Math.log((1 + f) / (1 - f)) * -scale;
	}

I notice that the two code varies. Shall we unified with same logic to improve maintenance ?

And in the second:

return Math.pow(2, zoom - 1) + 0.5 * Math.log((1 + f) / (1 - f)) * -scale;

-scale is wired, especially prefix with a *. Should we add a parenthesis?

[vulkd]

It looks like this was resolved by #7488 / #7570