Elements. Migrate PropertyElementResolver.

Change-Id: I0ce77ec9ae4ec5a3e3342a66a914fa8c5f837960
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/409203
Reviewed-by: Brian Wilkerson <[email protected]>
Reviewed-by: Phil Quitslund <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

pkg/analyzer/lib/src/dart/element/inheritance_manager3.dart

@@ -174,9 +174,9 @@ class InheritanceManager3 {
   /// This is equivalent to `getInheritedMap(type)[name]`.
   // This is a replacement for `getInherited2`.
   @experimental
-  ExecutableElement2? getInherited4(InterfaceElement2 element, Name name) {
+  ExecutableElement2OrMember? getInherited4(InterfaceElement2 element, Name name) {
     var oldElement = getInheritedMap2(element.asElement)[name];
-    return oldElement.asElement2;
+    return oldElement?.asElement2;
   }
 
   /// Returns signatures of all concrete members that the given [element]
@@ -375,7 +375,7 @@ class InheritanceManager3 {
   /// `class C extends S with M1, M2, M3`, only `S` and `M1` are considered.
   // This is a replacement for `getMember2`.
   @experimental
-  ExecutableElement2? getMember4(
+  ExecutableElement2OrMember? getMember4(
     InterfaceElement2 element,
     Name name, {
     bool concrete = false,

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

@@ -1032,7 +1032,7 @@ class InterfaceTypeImpl extends TypeImpl implements InterfaceType {
   }
 
   @override
-  GetterElement? lookUpGetter3(
+  GetterElement2OrMember? lookUpGetter3(
     String name,
     LibraryElement2 library, {
     bool concrete = false,
@@ -1142,7 +1142,7 @@ class InterfaceTypeImpl extends TypeImpl implements InterfaceType {
   }
 
   @override
-  SetterElement? lookUpSetter3(
+  SetterElement2OrMember? lookUpSetter3(
     String name,
     LibraryElement2 library, {
     bool concrete = false,