[css-logical-1] Close issue w3c#1519 per WG resolution.

Author: fantasai

css-logical-1/Overview.bs

@@ -81,9 +81,10 @@ Introduction</h2>
     <li><del>The 'float' and 'clear' keywords,
         because it is not yet clear what the upcoming 2-dimensional syntax of 'float' will be.</del>
         (This has been resolved as of April 2017.)
-    <li>The 'inset-*' properties,
+    <li><del>The 'inset-*' properties,
         because the name of the prefix is undecided.
-        (It used to be 'offset-*', but ended up conflicting with another CSS feature.)
+        (It used to be 'offset-*', but ended up conflicting with another CSS feature.)</del>
+        (This has been resolved as of June 2017.)
     <li>The ''border/logical'' keyword on shorthands,
         because the name of the keyword may change or it may be replaced by some other syntactic marker.
     <li>The 'background-image-transform' and 'border-image-transform' properties,