The shaping routine actually inspects the character buffer to do shaping. When synthesizing small caps, we correctly look up glyphs for the capitalized characters, but we need to keep those capitalized characters around in a buffer to pass to the shaper.
This is causing (at least) these 2 tests to fail: - fast/text/atsui-multiple-renderers.html - fast/text/atsui-small-caps-punctuation-size.html
<rdar://problem/115337519>