minor #12432 [CssSelector] Support *:only-of-type (hiddewie)

This PR was merged into the 4.4 branch.

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[CssSelector] Support *:only-of-type

#12425 and symfony/symfony#33861

![image](https://user-images.githubusercontent.com/1073881/66259057-0160f280-e7ad-11e9-9b1e-9558af79226b.png)

Commits
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00584d1 Remove exception for only-of-type selector

Author: javiereguiluz

components/css_selector.rst

@@ -93,9 +93,8 @@ rather than elements.
 
 Several pseudo-classes are not yet supported:
 
-* ``*:first-of-type``, ``*:last-of-type``, ``*:nth-of-type``,
-  ``*:nth-last-of-type``, ``*:only-of-type``. (These work with an element
-  name (e.g. ``li:first-of-type``) but not with ``*``).
+* ``*:first-of-type``, ``*:last-of-type``, ``*:nth-of-type`` and
+  ``*:nth-last-of-type``.
 
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