Fix type inference of getters that "override" setters and vice versa.

pkg/kernel/lib/src/incremental_class_hierarchy.dart

Index: pkg/kernel/lib/src/incremental_class_hierarchy.dart
diff --git a/pkg/kernel/lib/src/incremental_class_hierarchy.dart b/pkg/kernel/lib/src/incremental_class_hierarchy.dart
index ce13ecf920a1a26266853de87feee3e92ec959f4..051aae18f61db5692b6ed52f17ae05f4cff69569 100644
--- a/pkg/kernel/lib/src/incremental_class_hierarchy.dart
+++ b/pkg/kernel/lib/src/incremental_class_hierarchy.dart
@@ -86,8 +86,7 @@ class IncrementalClassHierarchy implements ClassHierarchy {
 
   @override
   void forEachOverridePair(Class node,
-      callback(Member declaredMember, Member interfaceMember, bool isSetter),
-      {bool crossGettersSetters: false}) {
+      callback(Member declaredMember, Member interfaceMember, bool isSetter)) {
     _ClassInfo info = _getInfo(node);
     for (var supertype in node.supers) {
       var superNode = supertype.classNode;
@@ -104,11 +103,6 @@ class IncrementalClassHierarchy implements ClassHierarchy {
           isSetter: true);
       _reportOverrides(info.declaredSetters, superSetters, callback,
           isSetter: true, onlyAbstract: true);
-
-      if (crossGettersSetters) {
-        _reportOverrides(info.declaredGettersAndCalls, superSetters, callback);
-        _reportOverrides(info.declaredSetters, superGetters, callback);
-      }
     }
     if (!node.isAbstract) {
       // If a non-abstract class declares an abstract method M whose
@@ -126,6 +120,24 @@ class IncrementalClassHierarchy implements ClassHierarchy {
     }
   }
 
+  @override
+  void forEachCrossOverridePair(Class node,
+      callback(Member declaredMember, Member interfaceMember, bool isSetter),
+      {bool crossGettersSetters: false}) {
+    _ClassInfo info = _getInfo(node);
+    for (var supertype in node.supers) {
+      var superNode = supertype.classNode;
+      var superInfo = _getInfo(superNode);
+
+      var superGetters = superInfo.interfaceGettersAndCalls;
+      var superSetters = superInfo.interfaceSetters;
+
+      _reportOverrides(info.declaredGettersAndCalls, superSetters, callback);
+      _reportOverrides(info.declaredSetters, superGetters, callback,
+          isSetter: true);
+    }
+  }
+
   @override
   Supertype getClassAsInstanceOf(Class node, Class superclass) {
     if (identical(node, superclass)) return node.asThisSupertype;