Bug 288394

Created attachment 474323 [details] html file to reproduce Fullscreen mode does not display the image specified in a <source> with media query display-mode: fullscreen. Steps to Reproduce: 1. Create an HTML page with the following code: <html> <head> <style> html, body{ margin:0; padding:0; } img { width: 100vw; height: 100vh; } </style> </head> <body> <picture onclick="requestFullscreen()"> <source media="(display-mode: fullscreen)" srcset="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAERlWElmTU0AKgAAAAgAAYdpAAQAAAABAAAAGgAAAAAAA6ABAAMAAAABAAEAAKACAAQAAAABAAAAAaADAAQAAAABAAAAAQAAAAD5Ip3+AAAADUlEQVQIHWNY8Z/hPwAGoQKnSTUSHQAAAABJRU5ErkJggg=="> <img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAERlWElmTU0AKgAAAAgAAYdpAAQAAAABAAAAGgAAAAAAA6ABAAMAAAABAAEAAKACAAQAAAABAAAAAaADAAQAAAABAAAAAQAAAAD5Ip3+AAAADUlEQVQIHWP4v5ThPwAG7wKkSFotfwAAAABJRU5ErkJggg=="/> </picture> </body> </html> 2. Click anywhere on the page (the image). Expected Behavior: the image from <source> with display-mode: fullscreen specified (greenish pixel) is displayed. Actual Behavior: The image specified in <img> (yellowish pixel) is displayed.