Don't apply `text-max-angle` check to line labels with `rotation-alignment: viewport`

Nobody has claimed this yet.

For now we use the version of Mapbox 0.47.0, in some cases we have a pretty long labels. In the new version of Mapbox 0.48.0 we see a regression associated with the fact that for all the same settings, the label at the same zoom level is not displayed, and to display it you need to zoom in to line.

**Mapbox 0.47.0**
**Mapbox 0.48.0**

**mapbox-gl-js version**: 0.48.0

### Link to Demonstration

Here’s the JSFiddle
for v.0.47.0: https://jsfiddle.net/iv_vo/g6q1rzot/
for v.0.48.0: https://jsfiddle.net/iv_vo/qrombvhf/

### Expected Behavior
Labels are shown at the same zoom level as before
### Actual Behavior
Labels are not shown at the same zoom level as before

Start by comparing the two JSFiddle demonstrations linked in the issue, using the Mapbox GL JS 0.47.0 and 0.48.0 versions to reproduce the label difference. Trace the line-label placement path related to `text-max-angle` and `rotation-alignment: viewport`; done means labels appear at the earlier zoom level without that check affecting them.

Written by the indexing model from the issue text.