chore(layer_drag_and_drop): remove extraneous comments
chore(layer_drag_and_drop): remove extraneous comments

janelia-flyem/neuroglancer,seung-lab/neuroglancer,janelia-flyem/neuroglancer,google/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer,seung-lab/neuroglancer,google/neuroglancer,seung-lab/neuroglancer,seung-lab/neuroglancer,seung-lab/neuroglancer,google/neuroglancer,google/neuroglancer,seung-lab/neuroglancer,google/neuroglancer,seung-lab/neuroglancer,janelia-flyem/neuroglancer,google/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer