Fix incorrect cursor positioning in Chrome.

Chrome has this quirk that cursor position reporting is correct only
if one of the composing keys it recognizes is hit, otherwise only
index 0 is always reliable.
Adjust candidate window with line height.

If the candidate window will be clipped by the screen, it will be
repositioned on top of the cursor. In that case, we need to move the
window further up by the composing text's line height plus some fixed
offset.
Bump to 1.0.8