Do not use qualifiedName property in KClass.cast function, because it's not supported in K/JS

Introduce an internal property that returns either qualified or simple name, and use it instead.

libraries/stdlib/js/src/kotlin/reflect/KClassesImpl.kt

@@ -0,0 +1,9 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package kotlin.reflect
+
+internal actual inline val KClass<*>.qualifiedOrSimpleName: String?
+    get() = simpleName

libraries/stdlib/jvm/src/kotlin/reflect/KClassesImpl.kt

@@ -0,0 +1,9 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package kotlin.reflect
+
+internal actual inline val KClass<*>.qualifiedOrSimpleName: String?
+    get() = qualifiedName

libraries/stdlib/src/kotlin/reflect/KClasses.kt

@@ -23,10 +23,13 @@ import kotlin.internal.LowPriorityInOverloadResolution
 @ExperimentalStdlibApi
 @LowPriorityInOverloadResolution
 fun <T : Any> KClass<T>.cast(value: Any?): T {
-    if (!isInstance(value)) throw ClassCastException("Value cannot be cast to $qualifiedName")
+    if (!isInstance(value)) throw ClassCastException("Value cannot be cast to $qualifiedOrSimpleName")
     return value as T
 }
 
+// TODO: replace with qualifiedName when it is fully supported in K/JS
+internal expect val KClass<*>.qualifiedOrSimpleName: String?
+
 /**
  * Casts the given [value] to the class represented by this [KClass] object.
  * Returns `null` if the value is `null` or if it is not an instance of this class.