Created attachment 308511 [details]
Variable GPOS test with shifting mark anchor
This reftest using an additional axis VM2B in the variabletest_box
font fails to work in WebKit nightly r215833. However, the *_expected.html file renders correctly.
The VM2B axis of this font shifts the mark anchor to the left, leading to the
combining mark SQUARE BELOW shifting right when the axis parameter is
adjusted from 0 to 1000. As the reference in the ref test, the font also
contains two additional glyphs N and O, which have fixed base anchors at
the middle and right position. A rendering of the M character showing
"m2b pos", followed by COMBINING SQUARE BELOW with VM2B 0, 500, 1000
applied must thus be equal to renderings of the N and O glyph with no
VM2B variation values applied.