`embolden` fails at 'i' glyph of Monaco font

[rhysd]

Here are screenshots of this issue.

• Non-bold text

• Bold text

Only the 'i' glyph fails to be emboldened. Other glyphs are correctly embolden. The glyph is actually thiner than the normal weight text so I think the winding was wrongly computed.

swash version: 0.2.10