Fix compilation errors

src/platform_impl/web/monitor.rs

@@ -1,5 +1,5 @@
 use crate::dpi::{PhysicalPosition, PhysicalSize};
-use crate::monitor::VideoMode;
+use crate::monitor::{MonitorHandle, VideoMode};
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct Handle;
@@ -26,3 +26,28 @@ impl Handle {
         std::iter::empty()
     }
 }
+
+#[derive(Derivative)]
+#[derivative(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Mode;
+
+impl Mode {
+    pub fn size(&self) -> PhysicalSize {
+        unimplemented!();
+    }
+
+    pub fn bit_depth(&self) -> u16 {
+        unimplemented!();
+    }
+
+    pub fn refresh_rate(&self) -> u16 {
+        32
+    }
+
+    pub fn monitor(&self) -> MonitorHandle {
+        MonitorHandle {
+            inner: Handle
+        }
+    }
+}
+