Suppose:
t1: 25% price-included, include_base_amount tax
t2: 12.5% price-included, include_base_amount tax
t3: 20.0% price-included, include_base_amount tax

Apply t1 & t3 on 300:
300 / 1.25 / 1.2 = 200 (total_excluded)
300 - 200 = 100 (tax_amount)

Apply the fiscal position mapping t1 to t2.
The price_unit is now computed from the total excluded (200) using t2 & t3:
Currently, you get:
200 + (200 * 0.125) + (200 * 0.20) = 200 + 25 + 40 = 265
Expected:
200 * 1.125 * 1.20 = 270

In this version, the reverse computation doesn't work well because we only manage it during the evaluation
of the prepared taxes computation. At this point, it's already too late because some dependencies between
taxes (implied by include_base_amount) are missing with reverse=True.

This commit replaces the 'reverse' flag by 'special_mode' because, for another purpose later, we will need
such kind of similar computation but with a different purpose. 'special_mode' has 3 possible values:
- `false`: That's the normal behavior of the taxes computation.
- `total_excluded`: Similar behavior as the `reverse` flag. In this mode, you are able to retrieve
the whole taxes computation by giving the total tax excluded amount as parameter.

Using our example, giving 200 with special_mode = 'total_excluded' will give you:
t1 = 60
t2 = 40
total_excluded = 200
total_included = 300

- `total_included`: Quite similar as `total_excluded` except you give the total tax included amount as parameter.

Using our example, giving 300 with special_mode = 'total_excluded' will give you:
t1 = 60
t2 = 40
total_excluded = 200
total_included = 300

---
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Before this commit, when opening a chatter with some activities with 2 or more tabs, the following crash occurs:

```
TypeError: recordFullProxy._fieldsValue.get is not a function
```

This happens because activities are shared between tabs, and the translation from structured records to data was leaking internal code `_fieldsValue`, which is used to map values of records that model Chatter data such as actvities.

Because `_fieldsValue` is a map and communication between tabs is made through `BroadcastChannel`, data are JSON.stringified and it is expected that reinsert of activity data works.

Maps like `_fieldsValue` were leaked, which turned the Map into an object, and since restore activity record in other tabs had an object for `_fieldsValue` instead of expected `Map`, it crashed.

This commit fixes the issue by not exposing `_fieldsValues` in the `toData()`, which is used by `BroadcastChannel` use of crosstab sync of activities. Also `toData()` had typos with relational fields which could also result in errors. These are also fixed in this commit.

When the user creates a new product with barcode and tries to save it,
a traceback will appear.

Steps to reproduce the error:
- Install "product_barcodelookup" module
- Add the API key for barcode lookup in settings
- Create new product > add barcode(ex. 817882025607) > Save

Traceback:
```
AttributeError: 'uom.uom' object has no attribute '_get_weight_uom_id_from_ir_config_parameter'
  File "odoo/http.py", line 2253, in __call__
    response = request._serve_db()
  File "odoo/http.py", line 1829, in _serve_db
    return self._transactioning(_serve_ir_http, readonly=ro)
  File "odoo/http.py", line 1849, in _transactioning
    return service_model.retrying(func, env=self.env)
  File "odoo/service/model.py", line 134, in retrying
    result = func()
  File "odoo/http.py", line 1827, in _serve_ir_http
    return self._serve_ir_http(rule, args)
  File "odoo/http.py", line 1834, in _serve_ir_http
    response = self.dispatcher.dispatch(rule.endpoint, args)
  File "odoo/http.py", line 2059, in dispatch
    result = self.request.registry['ir.http']._dispatch(endpoint)
  File "odoo/addons/base/models/ir_http.py", line 220, in _dispatch
    result = endpoint(**request.params)
  File "odoo/http.py", line 740, in route_wrapper
    result = endpoint(self, *args, **params_ok)
  File "addons/web/controllers/dataset.py", line 38, in call_kw
    return self._call_kw(model, method, args, kwargs)
  File "addons/web/controllers/dataset.py", line 34, in _call_kw
    return call_kw(request.env[model], method, args, kwargs)
  File "odoo/api.py", line 458, in call_kw
    result = getattr(recs, name)(*args, **kwargs)
  File "addons/web/models/models.py", line 1004, in onchange
    record._apply_onchange_methods(field_name, result)
  File "odoo/models.py", line 6879, in _apply_onchange_methods
    res = method(self)
  File "home/odoo/src/enterprise/saas-17.2/product_barcodelookup/models/product_template.py", line 17, in _onchange_barcode
    product._update_product_by_barcodelookup(product, product.barcode)
  File "home/odoo/src/enterprise/saas-17.2/product_barcodelookup/models/product_template.py", line 55, in _update_product_by_barcodelookup
    to_unit=self.env['uom.uom']._get_weight_uom_id_from_ir_config_parameter(),
```

https://github.com/odoo/enterprise/blob/058a2b63d3272d6b7fd52afba7951c56494b68f5/product_barcodelookup/models/product_template.py#L55 Here, "uom.uom" model has no _get_weight_uom_id_from_ir_config_parameter method.
so It will lead to the above traceback.

sentry-5373607708