Auto merge of #7817 - mbrubeck:prune, r=nox

Remove unused PostorderDomTraversal::should_prune

r? @pcwalton

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components/layout/traversal.rs

@@ -128,13 +128,6 @@ pub trait PostorderDomTraversal {
 pub trait PostorderNodeMutTraversal {
     /// The operation to perform. Return true to continue or false to stop.
     fn process<'a>(&'a mut self, node: &ThreadSafeLayoutNode<'a>) -> bool;
-
-    /// Returns true if this node should be pruned. If this returns true, we skip the operation
-    /// entirely and do not process any descendant nodes. This is called *before* child nodes are
-    /// visited. The default implementation never prunes any nodes.
-    fn should_prune<'a>(&'a self, _node: &ThreadSafeLayoutNode<'a>) -> bool {
-        false
-    }
 }
 
 /// The recalc-style-for-node traversal, which styles each node and must run before