Java to Kotlin converter: and even more smartness about nullability

#KT-5162 Fixed

j2k/tests/testData/ast/nullability/MethodInvokedWithTernaryNullArg.kt

@@ -0,0 +1,11 @@
+class C() {
+    private fun foo(s: String?) {
+    }
+
+    fun bar(b: Boolean) {
+        foo((if (b)
+            "a"
+        else
+            null))
+    }
+}