Add support for CASE_INSENSITIVE_ORDER in JS and common

#KT-18067

libraries/stdlib/jvm/src/kotlin/text/StringsJVM.kt

@@ -466,5 +466,5 @@ public actual fun CharSequence.repeat(n: Int): String {
  * Note that this Comparator does not take locale into account,
  * and will result in an unsatisfactory ordering for certain locales.
  */
-public val String.Companion.CASE_INSENSITIVE_ORDER: Comparator<String>
+public actual val String.Companion.CASE_INSENSITIVE_ORDER: Comparator<String>
     get() = java.lang.String.CASE_INSENSITIVE_ORDER

libraries/stdlib/jvm/test/text/StringJVMTest.kt

@@ -61,11 +61,6 @@ class StringJVMTest {
         assertArrayNotSameButEquals(charArrayOf('\u0000', '\u0000', 'e', 'l'), buffer)
     }
 
-    @Test fun orderIgnoringCase() {
-        val list = listOf("Beast", "Ast", "asterisk")
-        assertEquals(listOf("Ast", "Beast", "asterisk"), list.sorted())
-        assertEquals(listOf("Ast", "asterisk", "Beast"), list.sortedWith(String.CASE_INSENSITIVE_ORDER))
-    }
 
     @Test fun charsets() {
         assertEquals("UTF-32", Charsets.UTF_32.name())