Also, take a look at the prior work on this matter:

#2344

So the last patch makes bridge for subclasses work and no longer cuts of the prototype chain

class A { a() {return 'a'}}
class B extends A { b(){return 'b'}}
class C extends B { c(){return 'c'}}
Opal.klass(Opal.Kernel, C, 'C')

d = Opal.Kernel.C.$new()
d.c() -> 'c' - worked before
d.b() -> 'b'  - before b() was gone, now works
d.a() -> 'a' - before a() was gone, now works

There are still issues though

At this stage the following works:

require 'engine'
# Engine now allow access to globalThis, so in the browser for example
Engine.history.length # -> 2

manually in the browser console in js:

Engine.$send('history').$send('length') // -> 2

#send is required, because method_missing is used

further works:

require 'engine'
Engine.history.class.name # -> Engine::History

a = Engine::ArrayBuffer.new()
a.class.name # -> Engine::ArrayBuffer

the last one in js:

Opal.Engine.$const_get('ArrayBuffer').$new().$class().$name() // -> 'Engine::ArrayBuffer'

I kind of fail to understand what Opal::Engine does. Is it yet another wrapping solution? Wouldn't it be a better idea to split that to another PR?

Possibly, its handy for testing things, as its the goal to have automatic, easy and compact access to JS APIs and values. Once everything is working i may make that another PR or not, we will see

For correctness when using Engine for testing the bridges proeprties must be accessed by [], eg:

Engine[:history]
Engine[:history][:length]
Engine[:history].back

May work more or less, anymway
Continuing from here ...