Correctly extends the global Event interface

Author: MarshallOfSound

base/base_header.ts

@@ -4,3 +4,5 @@
 // Definitions: https://github.com/electron/electron-typescript-definitions
 
 /// <reference types="node" />
+
+type GlobalEvent = Event;

base/base_inner.ts

@@ -18,10 +18,10 @@
 
   }
 
-  interface Event {
-    preventDefault: Function;
+  interface Event extends GlobalEvent {
+    preventDefault: () => void;
     sender: WebContents;
-    returnValue?: any;
+    returnValue: any;
     ctrlkey?: boolean;
     metaKey?: boolean;
     shiftKey?: boolean;