Fix compilation errors

src/platform_impl/web/event_loop/proxy.rs

@@ -2,8 +2,7 @@ use super::runner;
 use crate::event::Event;
 use crate::event_loop::EventLoopClosed;
 
-#[derive(Clone)]
-pub struct Proxy<T: 'static> {
+pub struct Proxy<T: 'static>{
     runner: runner::Shared<T>,
 }
 
@@ -17,3 +16,11 @@ impl<T: 'static> Proxy<T> {
         Ok(())
     }
 }
+
+impl<T: 'static> Clone for Proxy<T> {
+    fn clone(&self) -> Self {
+        Proxy {
+            runner: self.runner.clone()
+        }
+    }
+}