Merge boxWithStdlib testData into box, delete BoxWithStdlib test

compiler/testData/codegen/box/boxingOptimization/variables.kt

@@ -0,0 +1,23 @@
+// WITH_RUNTIME
+
+import kotlin.test.assertEquals
+
+inline fun <R, T> foo(x : R, block : (R) -> T) : T {
+    var y = x
+    var z = y
+    z = x
+    return block(z)
+}
+
+fun box() : String {
+    assertEquals(1, foo(1) { x -> x })
+    assertEquals(1f, foo(1f) { x -> x })
+    assertEquals(1L, foo(1L) { x -> x })
+    assertEquals(1.toDouble(), foo(1.toDouble()) { x -> x })
+    assertEquals(1.toShort(), foo(1.toShort()) { x -> x })
+    assertEquals(1.toByte(), foo(1.toByte()) { x -> x })
+    assertEquals('a', foo('a') { x -> x })
+    assertEquals(true, foo(true) { x -> x })
+
+    return "OK"
+}