Remove more type casts

pkg/analyzer/lib/src/dart/constant/utilities.dart

Index: pkg/analyzer/lib/src/dart/constant/utilities.dart
diff --git a/pkg/analyzer/lib/src/dart/constant/utilities.dart b/pkg/analyzer/lib/src/dart/constant/utilities.dart
index c324d7fcb7fbb05a20f53572da191e8e9b3a70c9..80e736bbb358cc939ba17b3dc3d57a8fbebb83c7 100644
--- a/pkg/analyzer/lib/src/dart/constant/utilities.dart
+++ b/pkg/analyzer/lib/src/dart/constant/utilities.dart
@@ -290,10 +290,10 @@ class ReferenceFinder extends RecursiveAstVisitor<Object> {
 
   @override
   Object visitSimpleIdentifier(SimpleIdentifier node) {
-    Element element = node.staticElement;
-    if (element is PropertyAccessorElement) {
-      element = (element as PropertyAccessorElement).variable;
-    }
+    Element staticElement = node.staticElement;
+    Element element = staticElement is PropertyAccessorElement
+        ? staticElement.variable
+        : staticElement;
     if (element is VariableElement && element.isConst) {
       _callback(element);
     }