Issue when ImportAsset has an empty url #22018
Description
Describe the bug
This test SWF has 2 frames. Only the second frame has a symbol for an imported asset. The URL in the tag for the imported asset is an empty string ("").
On frame 1, nextFrame(); is called so that the movie immediately goes to frame 2. However, in Ruffle, this doesn't happen, because of the failure to load the imported asset. This is normally correct, however Flash Player doesn't seem to care when the URL for the asset is empty.
Expected behavior
Should move to frame 2 without problems.
Content Location
Affected platform
Desktop app
Operating system
macOS 15.6.1
Browser
No response
Additional information
This has caused a regression in an alternate version of one of Club Penguin's minigames, which has an ImportAssets tag with an empty URL (somehow), where it cannot move to the second frame which contains the actual gameplay.