Remove 'speculative evaluation' of predicates

Performing 'speculative evaluation' introduces caching bugs that
cannot be fixed without invasive changes to projection.

Hopefully, we can win back most of the performance lost by
re-adding 'cache completion'

Fixes #90662

src/test/ui/traits/issue-90662-projection-caching.rs

@@ -0,0 +1,34 @@
+// check-pass
+
+// Regression test for issue #90662
+// Tests that projection caching does not cause a spurious error
+
+trait HasProvider<T: ?Sized> {}
+trait Provider<M> {
+    type Interface: ?Sized;
+}
+
+trait Repository {}
+trait Service {}
+
+struct DbConnection;
+impl<M> Provider<M> for DbConnection {
+    type Interface = DbConnection;
+}
+
+struct RepositoryImpl;
+impl<M: HasProvider<DbConnection>> Provider<M> for RepositoryImpl {
+    type Interface = dyn Repository;
+}
+
+struct ServiceImpl;
+impl<M: HasProvider<dyn Repository>> Provider<M> for ServiceImpl {
+    type Interface = dyn Service;
+}
+
+struct TestModule;
+impl HasProvider<<DbConnection as Provider<Self>>::Interface> for TestModule {}
+impl HasProvider<<RepositoryImpl as Provider<Self>>::Interface> for TestModule {}
+impl HasProvider<<ServiceImpl as Provider<Self>>::Interface> for TestModule {}
+
+fn main() {}