This is similar to bug 125659 with even more bias centering. (probably should merge them)
innerTextRenderer->setLogicalTop(innerTextRenderer->logicalTop() - (logicalHeightDiff / 2 + layoutMod(logicalHeightDiff, 2)));
Check FF, prefer subpixel.
FF renders search widgets differently (search-vertical-alignment.html). The other 2 failed cases are not related and most likely result of some flakiness.
Prefer new behavior.