LibCore: Enable elapsed time as AK::Time on a ElapsedTimer

Userland/Libraries/LibCore/ElapsedTimer.cpp

@@ -34,4 +34,9 @@ int ElapsedTimer::elapsed() const
     return diff.tv_sec * 1000 + diff.tv_usec / 1000;
 }
 
+Time ElapsedTimer::elapsed_time() const
+{
+    return Time::from_milliseconds(elapsed());
+}
+
 }

Userland/Libraries/LibCore/ElapsedTimer.h

@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <AK/Time.h>
 #include <sys/time.h>
 
 namespace Core {
@@ -20,6 +21,7 @@ public:
     bool is_valid() const { return m_valid; }
     void start();
     int elapsed() const;
+    Time elapsed_time() const;
 
     const struct timeval& origin_time() const { return m_origin_time; }