* fix(editor): detect line height from the migrated font props on restore
The text branch of `restoreElement` parses the legacy `font` prop into local
`fontSize` and `fontFamily`, but line-height detection kept reading
`element.fontSize` and `element.fontFamily`. A diagram old enough to carry
`font` has neither, so `detectLineHeight` divided by `undefined` and the
element was restored with `lineHeight: NaN`. A non-numeric `height` produced
the same result.
Move the detection into `restoreLineHeight`, pass it the already-migrated
values, and fall back to the font family's fixed line height when the
detected value isn't a usable number.
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Signed-off-by: Mark Tolmacs <mark@lazycat.hu>
Co-authored-by: Mahiro Hirakawa <mahirohirakawa@glovrex.com>
