layout: Only create a LayoutContext if restyling (#37726)

The creation of `LayoutContext` does more work than necessary if layout
just needs to do something like make a display list and not restyle and
relayout. This change makes it so that these kind of non-restyle layouts
do not need to create a display list. In addition, the creation of
`LayoutContext` is better encapsulate

Testing: This should not change observable behavior and is thus covered
by existing WPT tests.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>
Co-authored-by: Oriol Brufau <obrufau@igalia.com>

components/layout/traversal.rs

@@ -20,11 +20,11 @@ pub struct RecalcStyle<'a> {
 }
 
 impl<'a> RecalcStyle<'a> {
-    pub fn new(context: &'a LayoutContext<'a>) -> Self {
+    pub(crate) fn new(context: &'a LayoutContext<'a>) -> Self {
         RecalcStyle { context }
     }
 
-    pub fn context(&self) -> &LayoutContext<'a> {
+    pub(crate) fn context(&self) -> &LayoutContext<'a> {
         self.context
     }
 }