System.dll into WebGL build

Hi,
following this article https://docs.unity3d.com/Manual/ReducingFilesize.html I removed all reference to system.dll from my code to size down webgl build but from log i discovered that library is however in the build.

I tried also with a empty project (only camera and a cube) and from editor log I get:
Mono dependencies included in the build
Dependency assembly - Mono.Security.dll
Dependency assembly - System.Core.dll
Dependency assembly - System.dll
Dependency assembly - mscorlib.dll
Dependency assembly - UnityEngine.UI.dll
Dependency assembly - UnityEngine.Networking.dll
Dependency assembly - UnityEngine.Timeline.dll
Dependency assembly - UnityEngine.Analytics.dll
Dependency assembly - UnityEngine.StandardEvents.dll

It's a bug?

I'm using 2017.4.4 LTS

 

Hi @Marco-Trivellato, how can i check if there are symbols from those DLLs in the generated build?

Starting from the basic project above I also tried to add a reference to a class in the system.dll (Queue <T>) and the build has a variation of 3KB (uncompressed).
So either the system.dll was also present in the initial version or striping is done inside the system.dll itself: In the latter case, however, it is something different from that in the documentation.
Did I make any mistakes? In which of the two cases are we?

I'm trying to make the webgl build as small as possible...

 

Hi, @Marco-Trivellato,
thanks for your answer.
I started from the basic project above with the script that uses queue <T> and Stopwatch (system.dll);
I tried the tool http://files.unity3d.com/build-report/
in the report does not appear neither "system" nor "queue" nor "Stopwatch"

Instead, opening <buildname> .asm.code.unityweb obviously I find for example Stopwatch
function _Stopwatch__cctor_m2429516881 (i1, i2) {
i1 = i1 | 0;
i2 = i2 | 0;
...
but this does not tell me if the whole library system is contained in the build

So i make another try and I realized that in a project that has queue but not stopwatch, in the build I do not find stopwatch (<buildname> .asm.code.unityweb). So unlike what is here https://docs.unity3d.com/Manual/ReducingFilesize.html striping seems also done inside the dll;
can you confirm it?
if so, you can use the classes you need, regardless of whether they are in the infamous system.dll