Border width is inconsistent at device pixel ratio 1.5

[SamRodri]

In Windows 10 with display scaling set to 150%, this Webrender snippet does not render correctly:

let border_side = BorderSide {
    color: ColorF::new(1.0, 0.0, 0.0, 1.0),
    style: BorderStyle::Solid,
};
let border_widths = LayoutSideOffsets::new_all_same(1.0);
let border_details = BorderDetails::Normal(NormalBorder {
    top: border_side,
    right: border_side,
    bottom: border_side,
    left: border_side,
    radius: BorderRadius::zero(),
    do_aa: true,
});
let bounds = LayoutRect::new(LayoutPoint::new(50.0, 50.0), LayoutSize::new(50.0, 50.0));
builder.push_border(
    &CommonItemProperties::new(
        bounds,
        SpaceAndClipInfo { spatial_id, clip_id: ClipId::root(pipeline_id) },
    ),
    bounds,
    border_widths,
    border_details,
);  

Servo also shows this bug servo#27457

[SamRodri]

I implemented pixel snapping in our layout pass and now everything renders correctly.

If there is no interest in handling misaligned input for borders in a more consistent fashion this issue can be closed.

[kvark]

Maybe @aosmond has an opinion on this :)

[nical]

Note that in gecko+WR we don't have this issue because border rectangle sizes are rounded when building the display list.