Merge pull request w3c#523 from cdoublev/pr-523

[css-compositing][css-masking] Force rendering whitespaces around combinators

Author: tabatkins

css-masking-1/Overview.bs

@@ -860,8 +860,16 @@ Media: visual
 Animation type: see individual properties
 </pre>
 
-<pre class=prod><dfn>&lt;mask-layer></dfn> = <<mask-reference>> || <<position>> [ / <<bg-size>> ]? ||
-    <<repeat-style>> || <<geometry-box>> || [ <<geometry-box>> | no-clip ] || <<compositing-operator>> || <<masking-mode>></pre>
+<pre class=prod>
+  <dfn>&lt;mask-layer></dfn> =
+    <<mask-reference>> ||
+    <<position>> [ / <<bg-size>> ]? ||
+    <<repeat-style>> ||
+    <<geometry-box>> ||
+    [ <<geometry-box>> | no-clip ] ||
+    <<compositing-operator>> ||
+    <<masking-mode>>
+</pre>
 
 If one <<geometry-box>> value and the ''no-clip'' keyword are present then <<geometry-box>> sets 'mask-origin' and ''no-clip'' sets 'mask-clip' to that value.