[element model] fix collection_methods_unrelated_type

Bug: https://github.com/dart-lang/linter/issues/5099
Change-Id: Ic3a6cdb344266b47a8f6b364298a673e71877595
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/393000
Commit-Queue: Phil Quitslund <[email protected]>
Auto-Submit: Phil Quitslund <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Brian Wilkerson <[email protected]>

Author: pq

pkg/linter/lib/src/rules/collection_methods_unrelated_type.dart

@@ -259,7 +259,7 @@ class _Visitor extends SimpleAstVisitor<void> {
 
       case _ExpectedArgumentKind.assignableToIterableOfTypeArgument:
         var iterableType =
-            collectionType.asInstanceOf(typeProvider.iterableElement);
+            collectionType.asInstanceOf2(typeProvider.iterableElement2);
         if (iterableType != null &&
             !typeSystem.isAssignableTo(argumentType, iterableType)) {
           rule.reportLint(argument, arguments: [