JS: move more test to box tests

js/js.translator/testData/box/number/intConversions.kt

@@ -0,0 +1,28 @@
+package foo
+
+fun box(): String {
+    val c: Int = 3
+    if (c.toDouble() != 3.0) {
+        return "fail1"
+    }
+    if (c.toFloat() != 3.toFloat()) {
+        return "fail2"
+    }
+    if (c.toByte() != 3.toByte()) {
+        return "fail3"
+    }
+    if (c.toInt() != 3) {
+        return "fail4"
+    }
+    if (c.toShort() != 3.toShort()) {
+        return "fail5"
+    }
+    val c2: Int = -5
+    if (c2.toShort() != (-5).toShort()) {
+        return "fail6"
+    }
+    if (c2.toFloat() != -5.toFloat()) {
+        return "fail7"
+    }
+    return "OK"
+}