Remove is_normalizable. Add sizedness_of to avoid layout_of que…

…ry on type aliases.

tests/ui/crashes/ice-10508.rs

@@ -0,0 +1,19 @@
+// Used to overflow in `is_normalizable`
+
+use std::marker::PhantomData;
+
+struct Node<T: 'static> {
+    m: PhantomData<&'static T>,
+}
+
+struct Digit<T> {
+    elem: T,
+}
+
+enum FingerTree<T: 'static> {
+    Single(T),
+
+    Deep(Digit<T>, Box<FingerTree<Node<T>>>),
+}
+
+fn main() {}