Check isnan Width and Height

[kassane]

based on D bindings: kassane/sokol-d#5 (comment)

cc: @floooh

[floooh]

Makes sense, yeah. I'll wait for the CI tests to go green (because I only see isnan() as C99 feature and wonder if C++ knows it too...

Do you know how those values became NaNs in the first place? If it's already mentioned in the thread just point me to the right comment :)

[floooh]

to the fact that the float/double in D is nan instead of 0.0f by default.

...wait does that mean that an unitialized float/double in D is initialized as NaN? That would be quite crazy because NaNs have a tendency to spread (they turn every expression result into NaNs too).

[floooh]

Ok all green and merged. Thanks!