Provide access to named groups of regex match result on JDK8.

#KT-12753 Fixed

libraries/stdlib/jre8/test/text/RegexTest.kt

@@ -0,0 +1,27 @@
+package kotlin.text.test
+
+import org.junit.Test
+import kotlin.test.*
+
+
+class RegexTest {
+    @Test fun namedGroups() {
+        val input = "1a 2b 3c"
+        val regex = "(?<num>\\d)(?<liter>\\w)".toRegex()
+
+        val matches = regex.findAll(input).toList()
+        assertTrue(matches.all { it.groups.size == 3 })
+        val m1 = matches[0]
+
+        assertEquals("1", m1.groups["num"]?.value)
+        assertEquals(0..0, m1.groups["num"]?.range)
+        assertEquals("a", m1.groups["liter"]?.value)
+        assertEquals(1..1, m1.groups["liter"]?.range)
+
+        val m2 = matches[1]
+        assertEquals("2", m2.groups["num"]?.value)
+        assertEquals(3..3, m2.groups["num"]?.range)
+        assertEquals("b", m2.groups["liter"]?.value)
+        assertEquals(4..4, m2.groups["liter"]?.range)
+    }
+}