infer null from context, this avoids bottom being introduced

pkg/analyzer/test/src/task/dart_test.dart

Index: pkg/analyzer/test/src/task/dart_test.dart
diff --git a/pkg/analyzer/test/src/task/dart_test.dart b/pkg/analyzer/test/src/task/dart_test.dart
index cedcb9b093be92ff5defc63d54fa37fd625b89c4..4891709e0029d1e12489077783eefdd63359cdb3 100644
--- a/pkg/analyzer/test/src/task/dart_test.dart
+++ b/pkg/analyzer/test/src/task/dart_test.dart
@@ -5421,15 +5421,15 @@ var tau = piFirst ? pi * 2 : 6.28;
     DartType dynamicType = context.typeProvider.dynamicType;
 
     assertVariableDeclarationTypes(
-        AstFinder.getTopLevelVariable(unit, "x"), dynamicType, bottomType);
+        AstFinder.getTopLevelVariable(unit, "x"), dynamicType, dynamicType);
     assertVariableDeclarationTypes(
         AstFinder.getTopLevelVariable(unit, "y"), intType, intType);
     assertVariableDeclarationTypes(
-        AstFinder.getFieldInClass(unit, "A", "x"), dynamicType, bottomType);
+        AstFinder.getFieldInClass(unit, "A", "x"), dynamicType, dynamicType);
     assertVariableDeclarationTypes(
         AstFinder.getFieldInClass(unit, "A", "y"), intType, intType);
     assertVariableDeclarationTypes(
-        AstFinder.getFieldInClass(unit, "A", "x2"), dynamicType, bottomType);
+        AstFinder.getFieldInClass(unit, "A", "x2"), dynamicType, dynamicType);
     assertVariableDeclarationTypes(
         AstFinder.getFieldInClass(unit, "A", "y2"), intType, intType);