Surprise empty default slot

[eddow]

Is your feature request related to a problem? Please describe.

When a component has a default slot and named slots, the textual line-break between named slots will be considered as the default slot.

Example:
MyComponent:

<slot name="slotA" />
<slot name="slotB" />
<slot>Default value</slot>

Usage:

<MyComponent>
    <div slot="slotA"> ... </div>
    <div slot="slotB"> ... </div>
</MyComponent>

This will define an empty default slot (the '⏎' in </div>⏎<div slot="slotB">) and "Default value" won't be displayed.
In order to use the default of the slot, we need to make sure there is no space between the named slots this way:

<MyComponent>
    <div slot="slotA">
        ...
    </div><div slot="slotB">
        ...
    </div>
</MyComponent>

Describe the solution you'd like
When the default slot value contains only spaces-like, the default should be used as if it was empty

How important is this feature to you?
annoyance-level + I had to search for some time why my slot didn't display

[dimfeld]

See #4546

[tanhauhau]

This should be fixed now in 3.35.0.

See REPL