background-color not filling full area of skybox panes

[jcarpenter]

When creating a skybox with background-size: 100%; and a different color for each pane, without using background images, the backgrounds do not fill the entire area of the pane. If I use an image instead of a color for each frame, the images work correctly (covering the entire pane).

Testing with Firefox Nightly June 30 CSS VR build. Same for mono and VR modes.

Test case: http://mozvr.github.io/cssvr-experiments/20150802-05/index.html

[jcarpenter]

For comparison, here is a test case that uses background-image for each pane:

http://mozvr.github.io/cssvr-experiments/20150802-06/index.html