Fixes gj/gk behaviour on wrapped lines; closes VSCodeVim#4120

This more or less reverts the functionality introduced by commit
4b2e079 and raised in issue VSCodeVim#3890.

Unfortunately it is not currently possible to fully implement display
line movements over wrapped lines that will always preserve cursor
position. One of two things is necessary to change this, either the
VSCode API needs to be extended to return information about wrapped
lines (but this was rejected in issue microsoft/vscode#23045).
Alternatively VSCodeVim would need to reïimplement all motions using
vscode.commands.executeCommand() commands rather than manipulating
vscode.window.activeTextEditor.selections directly, as the former
preserves column position while the latter does not. However it's not
clear to me if all VIM beahviour could be reïmplemented this way without
first trying this out and sounds like a bit of a ground up rewrite.

It seems for now we're stuck with gj/gk not preserving column position
when jumping across short lines.

src/actions/motion.ts

@@ -163,6 +163,19 @@ abstract class MoveByScreenLineMaintainDesiredColumn extends MoveByScreenLine {
   }
 }
 
+class MoveDownByScreenLineMaintainDesiredColumn extends MoveByScreenLineMaintainDesiredColumn {
+  movementType: CursorMovePosition = 'down';
+  by: CursorMoveByUnit = 'wrappedLine';
+  value = 1;
+}
+
+
+class MoveUpByScreenLineMaintainDesiredColumn extends MoveByScreenLineMaintainDesiredColumn {
+  movementType: CursorMovePosition = 'up';
+  by: CursorMoveByUnit = 'wrappedLine';
+  value = 1;
+}
+
 class MoveDownFoldFix extends MoveByScreenLineMaintainDesiredColumn {
   movementType: CursorMovePosition = 'down';
   by: CursorMoveByUnit = 'line';
@@ -785,7 +798,7 @@ class MoveScreenLineCenter extends MoveByScreenLine {
 }
 
 @RegisterAction
-export class MoveUpByScreenLineMaintainDesiredColumn extends MoveByScreenLineMaintainDesiredColumn {
+export class MoveUpByDisplayLine extends MoveByScreenLine {
   modes = [ModeName.Insert, ModeName.Normal, ModeName.Visual];
   keys = [['g', 'k'], ['g', '<up>']];
   movementType: CursorMovePosition = 'up';
@@ -794,7 +807,7 @@ export class MoveUpByScreenLineMaintainDesiredColumn extends MoveByScreenLineMai
 }
 
 @RegisterAction
-class MoveDownByScreenLineMaintainDesiredColumn extends MoveByScreenLineMaintainDesiredColumn {
+class MoveDownByDisplayLine extends MoveByScreenLine {
   modes = [ModeName.Insert, ModeName.Normal, ModeName.Visual];
   keys = [['g', 'j'], ['g', '<down>']];
   movementType: CursorMovePosition = 'down';

test/mode/modeVisual.test.ts

@@ -240,20 +240,6 @@ suite('Mode Visual', () => {
       keysPressed: 'vgjx',
       end: ['blah', 'duh', '|ur'],
     });
-
-    newTest({
-      title: "Preserves cursor position when handling 'gk'",
-      start: ['blah', 'word', 'a', 'la|st'],
-      keysPressed: 'vgkgkx',
-      end: ['blah', 'wo|t'],
-    });
-
-    newTest({
-      title: "Preserves cursor position when handling 'gj'",
-      start: ['blah', 'wo|rd', 'a', 'last'],
-      keysPressed: 'vgjgjx',
-      end: ['blah', 'wo|t'],
-    });
   });
 
   suite('handles aw in visual mode', () => {

test/mode/normalModeTests/motions.test.ts

@@ -739,18 +739,4 @@ suite('Motions in Normal Mode', () => {
     keysPressed: 'gj',
     end: ['blah', 'duh', 'dur', '|hur'],
   });
-
-  newTest({
-    title: "Preserves cursor position when handling 'gk'",
-    start: ['blah', 'duh', 'a', 'hu|r '],
-    keysPressed: 'gkgk',
-    end: ['blah', 'du|h', 'a', 'hur '],
-  });
-
-  newTest({
-    title: "Preserves cursor position when handling 'gj'",
-    start: ['blah', 'du|h', 'a', 'hur '],
-    keysPressed: 'gjgj',
-    end: ['blah', 'duh', 'a', 'hu|r '],
-  });
 });