Set font-variant-numeric: slashed-zero (#23416)

GitOrigin-RevId: 8a1ebecfe513226db75db431a05315064d6610d6

services/web/frontend/js/features/source-editor/extensions/theme.ts

@@ -179,6 +179,7 @@ const staticTheme = EditorView.theme({
   '&': {
     height: '100%',
     textRendering: 'optimizeSpeed',
+    fontVariantNumeric: 'slashed-zero',
   },
   // remove the outline from the focused editor
   '&.cm-editor.cm-focused:not(:focus-visible)': {