Because of css limitation, the child of a parent that define a
text-decoration cannot "neutralize" that decoration defined by its
parent with a css property (ie. the text-decoration cannot be
overridden).
When a block define an inline style or any tag that have a class, the
method `formatSelection` tries to "neutralize" the style by calling
`addNeutralStyle`. As it is impossible to "neutralize" the style for
underline nor strikeThrough, there is no method `addNeutralStyle`
defined for those properties.
Before this commit the method `formatSelection` was crashing because
`addNeutralStyle` was not defined.
Task-3002123
closesodoo/odoo#106635
X-original-commit: ce068a3113204dc558e69e88f1d2d778fa446c73
Signed-off-by: David Monjoie (dmo) <dmo@odoo.com>