Utilize built in f32 min function instead of custom implementation

[frewsxcv]

Replace

servo/components/layout/display_list_builder.rs

Lines 1931 to 1937 in dba1f27

	fn fmin(a: f32, b: f32) -> f32 {
	if a < b {
	a
	} else {
	b
	}
	}

with

https://doc.rust-lang.org/std/primitive.f32.html#method.min