JS backend: fixed the division operation for integral types.

#KT-2342 fixed

js/js.translator/testFiles/number/cases/kt2342.kt

@@ -0,0 +1,19 @@
+package foo
+
+fun test(a: Int, b: Int, expected: Int): String {
+  val result = a / b
+  if (expected == result) return "OK"
+  return "$a / $b = $result. Expected $expected"
+}
+
+fun box(): String {
+    var r = test(10, 3, 3)
+    if (r != "OK") return r
+
+    r = test(49, 6, 8)
+    if (r != "OK") return r
+
+    if (2133 / 3 / 7 / (91 / 5) != 5) return "2133 / 3 / 7 / (91 / 5) != 5"
+
+    return "OK"
+}