The main reason for removing this call is that this function is
deprecated, and is no longer needed now that we keep our own cache of
CTFonts that have been loaded from memory, and now that we no longer use
CoreText text layouts.
This also appears to fix an issue with garbled text which was
occasionally seen when different versions of the same font were
available, e.g. because differing versions of the font were
simultaneously embedded as BinaryData and installed on the system.
The glyph spacing for this font does not scale linearly with the font
size; at smaller font sizes, the spacing is relatively larger.
Typeface::getStringWidth, Typeface::getGlyphPositions, and the
equivalent Font member functions now take the font size and horizontal
scale into account when computing advances on Apple platforms.
