AnimationMixer signal don't emit when using custom timeline and time scale stretch

[ydeltastar]

Tested versions

v4.3.beta.custom_build [97b8ad1]

System information

Windows 11 - Vulkan (Forward+)

Issue description

Animation nodes in state machines have a use_custom_timeline and a stretch_time_scale that lets scale the animation to a custom length.

However, it breaks the animation_finished signal. Depending on the custom length I set, it becomes frame-dependent emitting on a 160hz monitor but not on a 60hz when the values are close, eg original length 0.4667 and custom length 0.4, or it doesn't emit at all the higher the difference, which in my tests, a few decimal places lower or higher.

Steps to reproduce

• In the MRP, "rotate_left" and "rotate_right" play and then transition to each other.
• Run. It should be printing "Animation finished rotate_right" every time "rotate_right" finishes but it doesn't work.
• Go to the state machine in the AnimationTree in "main.tscn", select the "rotate_right" animation node, and disable use_custom_timeline
• The signal now works and it prints.

Minimal reproduction project (MRP)

animation-signals.zip

[TokageItLab]

I think it is a floating point issue, similar to the problem I mentioned in #94372. For the code related to Animation, we may need a Math method for comparisons that takes into account the error of the double.