Expected Behavior

If you import gifs as costumes for a sprite it should import the images in the same order as they appear in the gif.

Actual Behavior

The images appear out of order. We fixed this issue (#4509) for sprite upload, but when you upload a gif as a costume they appear out of order.

related to issues: #3541 and #3254

Steps to Reproduce

Upload a relatively large gif with fluid motion such as this one:

Import the gif as a sprite
Build this stack:

Click the green flag
Note: the gif plays back smoothly
Now create a new empty sprite
Open the costumes tab
Choose Upload a costume
Choose the same gif
Add the same stack to this sprite
Click the green flag
Note: the gif jumps around because the images have come in out of order.

Here is a project I made to demonstrate, though to see the import behavior you will have to create a new one.

Operating System and Browser

Mac Chrome