[Gameplay] Galio W doesn't provoke heal from Twitch passive

Galio's W does not heal him when its target is being damaged by Twitch's passive. I realize that true damage has strange interactions with many other mechanics, but this one seems like it should work. The text of Galio's W tooltip states "whenever that unit suffers damage", which sounds like it would not ignore true damage.

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Full set of my unresolved bug report threads:

• Match History still calls north team "Purple"
• Team Builder lobby doesn't dissolve if an invited player disconnects
• Zyra passive can't be fired with an unranked ability's key
• Ahri R should start cooldown upon death
• Targeted abilities sometimes fizzle if their target moves away
• Storm Shield relics on Crystal Scar can be displaced
• Orianna's Ball may return while distance indicator is still yellow
• "Enable HUD animations" does nothing; "Disable minimap movement" ignores some input
• Galio W doesn't provoke heal from Twitch passive
• Teemo passive prevents capture of a neutral Twisted Treeline altar
• Anivia passive doesn't trigger if killed by Razorfins
• Vilemaw death timer not appearing
• Item Set construction doesn't properly label items' map availability
• Removed items are still displayed in Item Sets
• Zyra passive on quick cast is erratic
• Zyra can use trinket while in passive
• Inactive Heimerdinger turrets not damaged by Rift Herald

I will be bumping these threads periodically, though in a way that avoids flooding.