style: Rename LengthOrPercentage to LengthPercentage.

It does not represent `<length> | <percentage>`, but `<length-percentage>`, so
`LengthOrPercentage` is not the right name.

This patch is totally autogenerated using:

rg 'LengthOrPercentage' servo | cut -d : -f 1 | sort | uniq > files
for file in $(cat files); do sed -i "s#LengthOrPercentage#LengthPercentage#g" $file; done

Differential Revision: https://phabricator.services.mozilla.com/D15812

components/style/values/generics/box.rs

@@ -19,7 +19,7 @@ use crate::values::animated::ToAnimatedZero;
     ToComputedValue,
     ToCss,
 )]
-pub enum VerticalAlign<LengthOrPercentage> {
+pub enum VerticalAlign<LengthPercentage> {
     /// `baseline`
     Baseline,
     /// `sub`
@@ -40,7 +40,7 @@ pub enum VerticalAlign<LengthOrPercentage> {
     #[cfg(feature = "gecko")]
     MozMiddleWithBaseline,
     /// `<length-percentage>`
-    Length(LengthOrPercentage),
+    Length(LengthPercentage),
 }
 
 impl<L> VerticalAlign<L> {