This is a known Webkit bug — any text with
@font-face applied will be rendered without anti-aliasing if there is a text element without anti-aliasing applied preceding it. Usually those are fonts smaller than 5px or monospaced fonts at small sizes which are rendered without anti-aliasing.
I noticed this bug on this page — the heading “Kāzu ABC” was rendered aliased despite having the main menu in between that heading and the logo which had
font-size:1px; applied. The only way to fix this is by avoiding aliased text directly before elements that use @font-face.
Here is a live demo of the bug.