Changes/fixes:
- Added a detection routine for dark window colors on Windows 8 and later (system themes using dark window frames) to better adapt to dark system colors. Theme developers can take advantage of this by checking for darkwindowframe="true" on #main-window in CSS selectors.
- CSS classes prefixed with "--" no longer stop parsing of the selectors.
- Several crash fixes.
- Made GC suppression more aggressive to prevent issues when actually out of memory.
- Fixed a memory safety hazard in jpeg decoding.
- Fixed a potentially exploitable crash when using bi-directional text.
- Updated NSS to 3.19.4.2-PM, fixing CVE-2016-1938 among other things.