Even though we can opt-out of fixed-position compositing for unscrollable fixed-position containers, we still need to composite fixed-position layers that need compositing for other reasons such as overlap.
{
"layers": [
{
"name": "Scrolling background of LayoutView #document",
"bounds": [800, 4024],
"contentsOpaque": true,
"backgroundColor": "#FFFFFF"
},
{
"name": "LayoutBlockFlow (positioned) DIV class='absolute composited red box'",
"bounds": [100, 100],
"contentsOpaque": true,
"backgroundColor": "#FF0000",
"transform": 1
},
{
"name": "LayoutBlockFlow (positioned) DIV class='fixed lime box'",
"bounds": [100, 100],
"contentsOpaque": true,
"backgroundColor": "#00FF00",
"transform": 2
}
],
"transforms": [
{
"id": 1,
"transform": [
[1, 0, 0, 0],
[0, 1, 0, 0],
[0, 0, 1, 0],
[10, 100, 0, 1]
]
},
{
"id": 2,
"transform": [
[1, 0, 0, 0],
[0, 1, 0, 0],
[0, 0, 1, 0],
[10, 100, 0, 1]
]
}
]
}