Merge inline styles into one tag on output HTML

[Garry Yao]

Sometimes inline styles based on the same tag could be further optimized by combining them into one, i.e.

// font color + font size
<span style="font-size: 16px"><span style="color: #000000">This is my text.</span></span>

Could be output as

<span style="font-size: 16px;color: #000000">This is my text.</span>

Finally, this function should be configurable.

[Garry Yao]

We need to understand the necessity of this feature, do we have a strong request behind this? And when considering implementation, it's mostly only applicable on <span> but we have to employee a catch-all filter for doing that.

[Frederico Caldeira Knabben]

The most important reason for this is to have a more compact output from the editor. It's a valid request, but there is no priority for it.

[Jakub Ś]

This ticket plus #10675 is one large issue to change how styles are working.

#5503 is part of this ticket. It has been reported many times thus is has its own separate ticket.

[Jakub Ś]

Other issues can be found in #10742, #10675, #10824.

[Jakub Ś]

Ticket #6977 describes certain special case.

Not really sure if it should be applied here or not but perhaps should be also applied when font and span tags are used.

Additionally this case also mentions CSS rules that perhaps should also be merged background-color: rgb(130, 130, 130); and background-color:#ff0000;