function checkSetMap (texture) {
    // If the source has been changed, don't use loaded texture.
    if (shader.materialSrcs[materialName] !== src) { return; }
    setMap(texture);
  }
Update `material` texture property (usually but not always `map`)
from `data` property (usually but not always `src`)

@param {object} shader - A-Frame shader instance.
@param {object} data