map.loaded() seems broken for raster layers

[averas]

mapbox-gl-js version: v0.29.0

Steps to Trigger Behavior

1. Load Mapbox satellite
2. Interact (zoom/pan)
3. Check the status of map.loaded()

Go to http://codepen.io/anon/pen/mONqWz and wait for the map to be fully loaded. Check the status of map.loaded() by clicking on the "loaded" button and review the console output. Zoom in/out and pan the map around some and check again. After a while map.loaded() returns false and never recovers. You can also try the fly operation by clicking the fly button.

This messes up client code that depends on this state, such as Mapbox GL Draw which can't be added once the map starts returning false on map.loaded()

Expected Behavior

That map.loaded() returns true when it really is.

Actual Behavior

Returns false after some interaction.

[averas]

I confirmed this being related to #3398 and resolved in master via #3399.