Parcelable: Fix signature for Serializable Parcel serializer (KT-19749)

plugins/android-extensions/android-extensions-compiler/testData/parcel/box/kt19749.kt

@@ -0,0 +1,28 @@
+// WITH_RUNTIME
+
+@file:JvmName("TestKt")
+package test
+
+import kotlinx.android.parcel.*
+import android.os.Parcel
+import android.os.Parcelable
+import java.io.Serializable
+
+class MHelp(var m1: String): Serializable {
+    val m2 = 9
+}
+
+@Parcelize
+class M(val m: @RawValue MHelp) : Parcelable
+
+fun box() = parcelTest { parcel ->
+    val test = M(MHelp("A"))
+    test.writeToParcel(parcel, 0)
+
+    val bytes = parcel.marshall()
+    parcel.unmarshall(bytes, 0, bytes.size)
+
+    val test2 = readFromParcel<M>(parcel)
+
+    assert(test.m.m1 == test2.m.m1)
+}