Update debugger.log function

Definition of `debugger.log` should be less strict because definition of `console.log` is: `log(message?: any, ...optionalParams: any[]): void;`

types/debug/index.d.ts

@@ -38,7 +38,7 @@ declare namespace debug {
         (formatter: any, ...args: any[]): void;
 
         enabled: boolean;
-        log: (v: any) => string;
+        log: (args: any[]) => any;
         namespace: string;
         extend: (namespace: string, delimiter?: string) => Debugger;
     }