Stop propagating return types for top-level function declarations

pkg/analyzer/lib/src/generated/static_type_analyzer.dart

Index: pkg/analyzer/lib/src/generated/static_type_analyzer.dart
diff --git a/pkg/analyzer/lib/src/generated/static_type_analyzer.dart b/pkg/analyzer/lib/src/generated/static_type_analyzer.dart
index bffeaadc6ec92b39364d1d1b2ca2a507b2efb889..3da6e37dde38cd8be063f5e9ba6bffabd0fef6c4 100644
--- a/pkg/analyzer/lib/src/generated/static_type_analyzer.dart
+++ b/pkg/analyzer/lib/src/generated/static_type_analyzer.dart
@@ -328,7 +328,9 @@ class StaticTypeAnalyzer extends SimpleAstVisitor<Object> {
         node.element as ExecutableElementImpl;
     functionElement.returnType =
         _computeStaticReturnTypeOfFunctionDeclaration(node);
-    _recordPropagatedTypeOfFunction(functionElement, function.body);
+    if (node.parent is FunctionDeclarationStatement) {
+      _recordPropagatedTypeOfFunction(functionElement, function.body);
+    }
     _recordStaticType(function, functionElement.type);
     return null;
   }