Remove more type casts

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

Index: pkg/analyzer/lib/src/generated/incremental_resolver.dart
diff --git a/pkg/analyzer/lib/src/generated/incremental_resolver.dart b/pkg/analyzer/lib/src/generated/incremental_resolver.dart
index d0620ca7d847c6516e299222e2973123be3ff5f1..2b98d4aac8180a02c8f96616c0214d51599e9c2a 100644
--- a/pkg/analyzer/lib/src/generated/incremental_resolver.dart
+++ b/pkg/analyzer/lib/src/generated/incremental_resolver.dart
@@ -423,8 +423,9 @@ class DeclarationMatcher extends RecursiveAstVisitor {
         (node.parent as VariableDeclarationList).type, element.type);
     // matches, restore the existing element
     node.name.staticElement = element;
-    if (element is VariableElementImpl) {
-      (element as VariableElementImpl).initializer = newElement.initializer;
+    Element variable = element;
+    if (variable is VariableElementImpl) {
+      variable.initializer = newElement.initializer;
     }
   }