[dvipdfmx] Color stacks and transformations

[Joseph Wright]

Hello all,

Initially reported to me as a graphics-def bug 
(https://github.com/latex3/graphics-def/issues/26), it seems that the 
new color stacks don't mix well with transformations. In the example

     \special{pdfcolorstackinit 1 page direct (0 g 0 G)}%
     \special{pdfcolorstack 1 push (1 0 0 rg)}%
     \special{x:gsave}\special{x:rotate 0}%
     %\special{pdf:btrans rotate 0}%
     A%
     %\special{pdf:etrans}%
     \special{x:grestore}%
     B%
     \special{pdfcolorstack 1 pop}%
     \bye

using either type of special, the "B" looses color. The same is true 
using x:scale, etc. This doesn't happen with the single stack 
bcolor/ecolor approach, so I think is because the interplay between the 
new color and transformations isn't quite right.

Joseph