KT-2193 Nullability information lost for functions inherited from traits

#KT-2193 fixed

compiler/testData/codegen/traits/inheritedFun.jet

@@ -0,0 +1,10 @@
+//KT-2206
+trait A {
+    fun f():Int = 239
+}
+
+class B() : A
+
+fun box() : String {
+    return if (B().f() == 239) "OK" else "fail"
+}

compiler/testData/codegen/traits/inheritedVar.jet

@@ -0,0 +1,14 @@
+//KT-2206
+
+trait A {
+    var a:Int
+        get() = 239
+        set(value) {
+        }
+}
+
+class B() : A
+
+fun box() : String {
+    return if (B().a == 239) "OK" else "fail"
+}