Merge pull request #8523 from benthayer/backspace-simplify

Simplified multicursor backspace code

packages/codemirror/src/editor.ts

@@ -1399,18 +1399,8 @@ namespace Private {
           doc.replaceRange('', from, head);
         } else {
           // delete non-tabs
-          if (head.ch === 0) {
-            if (head.line !== 0) {
-              const from = CodeMirror.Pos(
-                head.line - 1,
-                doc.getLine(head.line - 1).length
-              );
-              doc.replaceRange('', from, head);
-            }
-          } else {
-            const from = CodeMirror.Pos(head.line, head.ch - 1);
-            doc.replaceRange('', from, head);
-          }
+          const from = cm.findPosH(head, -1, 'char', false);
+          doc.replaceRange('', from, head);
         }
       }
     }