JS: fixed <Type>Array.iterator methods; added -Xtypedarray compiler key

The <Type>Array.iterator used to lack next<Type>() method (KT-16626).

The -Xtypedarray compiler key enables translation of primitive arrays
to TypedArrays, and primitive array`is`-checks (KT-15358, KT-14007,
KT-14614, KT-16056).

compiler/testData/codegen/box/arrays/kt7288.kt

@@ -1,3 +1,5 @@
+// IGNORE_BACKEND_WITHOUT_CHECK: JS
+
 fun test(b: Boolean): String {
     val a = if (b) IntArray(5) else LongArray(5)
     if (a is IntArray) {