LibJS: Implement console.assert()

Author: https://github.com/linusg
Commit: 8d490aba76
Pull-request: https://github.com/SerenityOS/serenity/pull/6454
Reviewed-by: https://github.com/alimpfard

Userland/Libraries/LibJS/Runtime/ConsoleObject.h

@@ -48,6 +48,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(count);
     JS_DECLARE_NATIVE_FUNCTION(count_reset);
     JS_DECLARE_NATIVE_FUNCTION(clear);
+    JS_DECLARE_NATIVE_FUNCTION(assert_);
 };
 
 }