Don't require to override abstract methods in expect class

#KT-16099 Fixed

core/descriptors/src/org/jetbrains/kotlin/resolve/DescriptorUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2016 JetBrains s.r.o.
+ * Copyright 2010-2017 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -458,7 +458,11 @@ public class DescriptorUtils {
                KotlinTypeChecker.DEFAULT.equalTypes(builtIns.getAnyType(), type);
     }
 
-    public static boolean classCanHaveAbstractMembers(@NotNull ClassDescriptor classDescriptor) {
+    public static boolean classCanHaveAbstractFakeOverride(@NotNull ClassDescriptor classDescriptor) {
+        return classCanHaveAbstractDeclaration(classDescriptor) || classDescriptor.isExpect();
+    }
+
+    public static boolean classCanHaveAbstractDeclaration(@NotNull ClassDescriptor classDescriptor) {
         return classDescriptor.getModality() == Modality.ABSTRACT
                || isSealedClass(classDescriptor)
                || classDescriptor.getKind() == ClassKind.ENUM_CLASS;