When setting texture priorities, sprites that should not have textures get them anyway

[okaybenji]

This Issue is about

• A bug in the API:
  • Phaser version(s): Phaser CE v2.7.10
  • Live example: https://codepen.io/okaybenji/pen/qmgazJ
  • What should happen: Creating a sprite without passing a key to the constructor should create a textureless sprite.
  • What happens instead: The new sprite gets whatever texture was used last.

I don't believe this is the expected behavior, because if you don't set the texture priority, the sprite will be textureless.

[samme]

Adding __default to the setTexturePriority list seems to "fix" the example — unless the second sprite's key is also __default.

The problem seems to be that prioritized textures get drawn onto sprites where they don't belong, same as #231.

[samme]

https://codepen.io/samme/pen/GEQmOy

[samme]

Appears fixed by #641

https://codepen.io/samme/pen/JjoeGaW