[FIX] pos_mercury: support for Inernet Explorer / Edge
[FIX] pos_mercury: support for Inernet Explorer / Edge

In the method `xml_node_to_string` in `qweb2.js`,
which is used when extending XML templates,
such as this extend of the template `PaymentScreen-Paymentlines`

the method `(new XMLSerializer()).serializeToString(node)`
magically escapes the double quotes `"` in Internet Explorer and Edge,
while this is not the case in other browsers,
therefore converting, for instance,
`this.removeAttr("class");`
to
`this.removeAttr(&quote;class&quote;);`
whhich made the rendering of the template fails.

As this method is quite critical, we do not dare
editing it to use an alternative to `XMLSerializer.serializeToString`
in a stable release

Instead, as a workaround, we just avoid the use of the double
quotes.

opw-708296

ygol/odoo,hip-odoo/odoo,hip-odoo/odoo,bplancher/odoo,ygol/odoo,ygol/odoo,ygol/odoo,bplancher/odoo,hip-odoo/odoo,hip-odoo/odoo,Elico-Corp/odoo_OCB,ygol/odoo,Elico-Corp/odoo_OCB,ygol/odoo,bplancher/odoo,hip-odoo/odoo,hip-odoo/odoo,Elico-Corp/odoo_OCB,Elico-Corp/odoo_OCB,Elico-Corp/odoo_OCB,Elico-Corp/odoo_OCB,bplancher/odoo,ygol/odoo,bplancher/odoo,bplancher/odoo