servo: Merge #19692 - style: Make Contain::parse simpler (from stevel98:Contain); r=emilio

<!-- Please describe your changes on the following line: -->
---
Makes Contain::parse slightly simpler, as discussed in #19682

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #19682 (github issue number if applicable).

<!-- Either: -->
- [ ] There are tests for these changes OR
- [X] These changes do not require tests because refactoring

Source-Repo: https://github.com/servo/servo
Source-Revision: 0393f9d231ce146761ed6b6b635ac040adfb07f3

--HG--
extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear
extra : subtree_revision : 80573b78a8a266eec84f2b72ac157491219425c8

servo/components/style/values/specified/box.rs

@@ -553,18 +553,8 @@ impl Parse for Contain {
                 "layout" => Some(Contain::LAYOUT),
                 "style" => Some(Contain::STYLE),
                 "paint" => Some(Contain::PAINT),
-                "strict" => {
-                    if result.is_empty() {
-                        return Ok(Contain::STRICT | Contain::STRICT_BITS)
-                    }
-                    None
-                },
-                "none" => {
-                    if result.is_empty() {
-                        return Ok(result)
-                    }
-                    None
-                },
+                "strict" if result.is_empty() => return Ok(Contain::STRICT | Contain::STRICT_BITS),
+                "none" if result.is_empty() => return Ok(result),
                 _ => None
             };