[element model] migrate unnecessary_null_checks

Bug: https://github.com/dart-lang/linter/issues/5099
Change-Id: I029a4f40344c179ba205a73b453da639452b220f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/390264
Reviewed-by: Brian Wilkerson <[email protected]>
Auto-Submit: Phil Quitslund <[email protected]>
Commit-Queue: Phil Quitslund <[email protected]>

Author: pq

pkg/linter/analyzer_use_new_elements.txt

@@ -25,7 +25,6 @@ lib/src/rules/avoid_function_literals_in_foreach_calls.dart
 lib/src/rules/avoid_implementing_value_types.dart
 lib/src/rules/avoid_js_rounded_ints.dart
 lib/src/rules/avoid_multiple_declarations_per_line.dart
-lib/src/rules/avoid_null_checks_in_equality_operators.dart
 lib/src/rules/avoid_print.dart
 lib/src/rules/avoid_private_typedef_functions.dart
 lib/src/rules/avoid_relative_lib_imports.dart
@@ -233,6 +232,7 @@ test/rules/avoid_implementing_value_types_test.dart
 test/rules/avoid_init_to_null_test.dart
 test/rules/avoid_js_rounded_ints_test.dart
 test/rules/avoid_multiple_declarations_per_line_test.dart
+test/rules/avoid_null_checks_in_equality_operators_test.dart
 test/rules/avoid_positional_boolean_parameters_test.dart
 test/rules/avoid_print_test.dart
 test/rules/avoid_private_typedef_functions_test.dart

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

@@ -65,15 +65,16 @@ DartType? getExpectedType(PostfixExpression node) {
   }
   // in variable declaration
   if (parent is VariableDeclaration) {
-    return parent.declaredElement?.type;
+    var element = parent.declaredFragment?.element ?? parent.declaredElement2;
+    return element?.type;
   }
   // as right member of binary operator
   if (parent is BinaryExpression && parent.rightOperand == realNode) {
-    var parentElement = parent.staticElement;
+    var parentElement = parent.element;
     if (parentElement == null) {
       return null;
     }
-    return parentElement.parameters.first.type;
+    return parentElement.formalParameters.first.type;
   }
   // as member of list
   if (parent is ListLiteral) {
@@ -107,7 +108,7 @@ DartType? getExpectedType(PostfixExpression node) {
   if (parent is ArgumentList && realNode is Expression) {
     var grandParent = parent.parent;
     if (grandParent is InstanceCreationExpression) {
-      var constructor = grandParent.constructorName.staticElement;
+      var constructor = grandParent.constructorName.element;
       if (constructor != null) {
         if (constructor.returnType.isDartAsyncFuture &&
             constructor.name == 'value') {
@@ -126,7 +127,7 @@ DartType? getExpectedType(PostfixExpression node) {
         }
       }
     }
-    return realNode.staticParameterElement?.type;
+    return realNode.correspondingParameter?.type;
   }
   return null;
 }