Line Height is not reduced after reducing the font size

[rishi]

1. Set the font size to 72 and type "abcdef" in the CKEditor
2. Press Enter
3. Now the source in CKE will be

   <p><span style="font-size:72px">asdsadsadasd</span></p>
   

4. Select only "abc" change the font size to 8. This time source will be:

   <p><span style="font-size:72px"><span style="font-size:8px">abc</span>def</span></p>
   

4. Now, select "def" and change the font size also to 8. This time source will be:

   <p><span style="font-size:72px"><span style="font-size:8px">abcdef</span></span></p>
   

Expected:

<span style="font-size:72px">

span tag shuld be deleted in step 4.

Due this the line hieght is set to 72 px. This should be fixed.

[Jakub Ś]

This is a DUP of #10675.

Ticket #10675 is one big issue that talks about merging and normalizing styles. This looks like one of these cases that should be handled by #10675.