Elements. For FormalParameterFragment enclosingFragment can be another FormalParameterFragment, not only ExecutableFragment.

Change-Id: I2aa32b088ad77a41e4b40d406488a12da126f52d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/398945
Reviewed-by: Phil Quitslund <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: scheglov

pkg/analyzer/lib/dart/element/element2.dart

@@ -2183,9 +2183,6 @@ abstract class PromotableFragment implements VariableFragment {
   @override
   PromotableElement2 get element;
 
-  @override
-  ExecutableFragment? get enclosingFragment;
-
   @override
   PromotableFragment? get nextFragment;
 

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

@@ -8869,8 +8869,7 @@ class ParameterElementImpl extends VariableElementImpl
   set element(FormalParameterElement element) => _element = element;
 
   @override
-  ExecutableFragment? get enclosingFragment =>
-      enclosingElement3 as ExecutableFragment?;
+  Fragment? get enclosingFragment => enclosingElement3 as Fragment?;
 
   @override
   bool get hasDefaultValue {