fix: macos sizing unmaximized window incorrectly

https://chromium-review.googlesource.com/c/chromium/src/+/7487666

Changes to headless mode caused the unmaximized window to subtract
the height of the menubar.

shell/browser/ui/cocoa/electron_ns_window.mm

@@ -320,7 +320,7 @@ void SwizzleSwipeWithEvent(NSView* view, SEL swiz_selector) {
 }
 
 - (void)disableHeadlessMode {
-  if (shell_) {
+  if (shell_ && self.isHeadless) {
     // We initialize the window in headless mode to allow painting before it is
     // shown, but we don't want the headless behavior of allowing the window to
     // be placed unconstrained.