Remove some conflicting declarations from test, convert code to new Regex API

js/js.translator/testData/reservedWords/_commonFiles/helpers.kt

@@ -1,25 +1,17 @@
 package foo
 
+import kotlin.text.Regex
+
 fun testRenamed(case: String, f: () -> Unit) = test(case, true, f)
 fun testNotRenamed(case: String, f: () -> Unit) = test(case, false, f)
 
-native
-fun String.replace(r: String, s: String): String = noImpl
-
-native
-class RegExp(pattern: String, flag: String)
-
-native
-fun String.match(r: RegExp): Array<String> = noImpl
-
 fun test(keyword: String, expectedRenamed: Boolean, f: Any) {
     val fs = f.toString().replace("while (false)", "")
-    val matches = fs.match(RegExp("[\\w$]*$keyword[\\w_$]*", "g"))
+    val matches = Regex("[\\w$]*$keyword[\\w_$]*").matchAll(fs).map { it.value }.toList()
 
-    assertNotEquals(null, matches, "matches == null, fs = $fs")
-    assertNotEquals(0, matches.size, "matches = $matches")
+    assertNotEquals(0, matches.size(), "matches is empty for fs = $fs")
 
-    val actual = matches[matches.size -1]
+    val actual = matches.last()
 
     assertTrue(actual.contains(keyword), "'$keyword' not found in '$matches' from '$fs'")