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

pkg/analyzer/lib/src/summary/link.dart

Index: pkg/analyzer/lib/src/summary/link.dart
diff --git a/pkg/analyzer/lib/src/summary/link.dart b/pkg/analyzer/lib/src/summary/link.dart
index e261675b485dec79507eb4912905ad22a4b666ca..a685504be5cbc9ab8b18aacfae880c24708a91de 100644
--- a/pkg/analyzer/lib/src/summary/link.dart
+++ b/pkg/analyzer/lib/src/summary/link.dart
@@ -247,7 +247,7 @@ EntityRefBuilder _createLinkedType(
 }
 
 DartType _dynamicIfNull(DartType type) {
-  if (type == null || type.isBottom || type.isVoid) {
+  if (type == null || type.isBottom || type.isDartCoreNull || type.isVoid) {
     return DynamicTypeImpl.instance;
   }
   return type;
@@ -2006,7 +2006,7 @@ class ExprTypeComputer {
           stack.add(typeProvider.symbolType);
           break;
         case UnlinkedExprOperation.pushNull:
-          stack.add(BottomTypeImpl.instance);
+          stack.add(typeProvider.nullType);
           break;
         case UnlinkedExprOperation.pushReference:
           _doPushReference();