Use u32 for generation numbers.

components/layout/context.rs

@@ -86,7 +86,7 @@ pub struct SharedLayoutContext {
 
     /// Starts at zero, and increased by one every time a layout completes.
     /// This can be used to easily check for invalid stale data.
-    pub generation: uint,
+    pub generation: u32,
 }
 
 pub struct SharedLayoutContextWrapper(pub *const SharedLayoutContext);

components/layout/layout_task.rs

@@ -107,7 +107,7 @@ pub struct LayoutTaskData {
 
     /// Starts at zero, and increased by one every time a layout completes.
     /// This can be used to easily check for invalid stale data.
-    pub generation: uint,
+    pub generation: u32,
 
     /// A queued response for the union of the content boxes of a node.
     pub content_box_response: Rect<Au>,

components/layout/traversal.rs

@@ -28,7 +28,7 @@ use std::mem;
 
 /// Every time we do another layout, the old bloom filters are invalid. This is
 /// detected by ticking a generation number every layout.
-type Generation = uint;
+type Generation = u32;
 
 /// A pair of the bloom filter used for css selector matching, and the node to
 /// which it applies. This is used to efficiently do `Descendant` selector