JS backend: fix KT-5738 JS backend: result of toByte() should be in the range of bytes

#KT-5738 Fixed

js/js.tests/test/org/jetbrains/k2js/test/semantics/NumberTest.java

@@ -69,4 +69,12 @@ public final class NumberTest extends SingleFileTranslationTest {
     public void testNumberCompareTo() throws Exception {
         checkFooBoxIsOk();
     }
+
+    public void testConversionsWithoutTruncation() throws Exception {
+        checkFooBoxIsOk();
+    }
+
+    public void testConversionsWithTruncation() throws Exception {
+        checkFooBoxIsOk();
+    }
 }