Issue 28027. Move Null to the bottom in the Analyzer.

pkg/analyzer/lib/src/dart/element/type.dart

Index: pkg/analyzer/lib/src/dart/element/type.dart
diff --git a/pkg/analyzer/lib/src/dart/element/type.dart b/pkg/analyzer/lib/src/dart/element/type.dart
index dab72dcd6a70cc0dc0a8eb023013f18297cc3e36..c1feff9e4553d795f1e3cf4d195c9f937f4c4673 100644
--- a/pkg/analyzer/lib/src/dart/element/type.dart
+++ b/pkg/analyzer/lib/src/dart/element/type.dart
@@ -1598,6 +1598,12 @@ class InterfaceTypeImpl extends TypeImpl implements InterfaceType {
   bool isMoreSpecificThan(DartType type,
       [bool withDynamic = false, Set<Element> visitedElements]) {
     //
+    // T is Null and S is not Bottom.
+    //
+    if (isDartCoreNull && !type.isBottom) {
+      return true;
+    }
+
     // S is dynamic.
     // The test to determine whether S is dynamic is done here because dynamic
     // is not an instance of InterfaceType.