vim: Fix ctrl-d/u going to top bottom (#14620)

Release Notes:

- vim: Fixed ctrl-d/ctrl-u getting to top/bottom of buffer (#13250)

crates/editor/src/scroll/scroll_amount.rs

@@ -1,4 +1,3 @@
-use crate::Editor;
 use serde::Deserialize;
 use ui::{px, Pixels};
 
@@ -11,19 +10,16 @@ pub enum ScrollAmount {
 }
 
 impl ScrollAmount {
-    pub fn lines(&self, editor: &mut Editor) -> f32 {
+    pub fn lines(&self, mut visible_line_count: f32) -> f32 {
         match self {
             Self::Line(count) => *count,
-            Self::Page(count) => editor
-                .visible_line_count()
-                .map(|mut l| {
-                    // for full pages subtract one to leave an anchor line
-                    if count.abs() == 1.0 {
-                        l -= 1.0
-                    }
-                    (l * count).trunc()
-                })
-                .unwrap_or(0.),
+            Self::Page(count) => {
+                // for full pages subtract one to leave an anchor line
+                if count.abs() == 1.0 {
+                    visible_line_count -= 1.0
+                }
+                (visible_line_count * count).trunc()
+            }
         }
     }