SCUMM/HE: Flashing line at bottom of screen in Freddi 3

[Thunderforge]

In Freddi Fish 3: The Case of the Stolen Conch Shell, there is a situation in which a flashing line appears at the bottom of screen during some dialogue.

Reproduction Steps

1. Open the debugger and type in room 17
2. Click on the pink fish on the rope in the upper left corner of the screen (do not click on the clam to cut the rope)
3. Luther will say "Gee, that fish looks like it's really hungry for those kelp vines."

During Luther's dialogue, the very bottom of the sreen will have a flashing line. See attached animated GIF

Versions tested

• Freddi Fish 3: Steam release
• ScummVM 2.6.0 nightly 2022-06-02

[Thunderforge]

Turns out this *doesn't* happen in the English-UK version of the game, but it does in the English-US version.

[AndywinXp]

I have verified that this happens in the original executable too. It's probably a corrupt data file (maybe one of Luther's lipsync frames?).

Please mark it as enhancement when fixing it!

[AndywinXp]

In 59f752c0:

SCUMM: HE/FREDDI3: Provide better solution for bug #13532

"SCUMM/HE: Flashing line at bottom of screen in Freddi 3"

This solves #13532 in a better way: instead of moving the
animation down by one pixel, we simply avoid marking that
line of stray pixels as part of the dirty rectangle.

We remove two pixels since AkosRenderer::paintCelByleRLE()
is going to add one pixel to the rect during the clipping part.