Add startsWith()/endsWith(). (#281)

backend.native/tests/build.gradle

@@ -879,7 +879,7 @@ task string_builder0(type: RunKonanTest) {
 }
 
 task string0(type: RunKonanTest) {
-    goldValue = "true\ntrue\nПРИВЕТ\nпривет\nПока\n"
+    goldValue = "true\ntrue\nПРИВЕТ\nпривет\nПока\ntrue\n"
     source = "runtime/text/string0.kt"
 }
 

backend.native/tests/runtime/text/string0.kt

@@ -6,4 +6,5 @@ fun main(args: Array<String>) {
     println(strI18n.toUpperCase())
     println(strI18n.toLowerCase())
     println("пока".capitalize())
+    println("http://jetbrains.com".startsWith("http://"))
 }