Get rid of deprecated annotations and modifiers in stdlib (besides JS)

libraries/stdlib/test/text/StringBuilderTest.kt

@@ -5,7 +5,7 @@ import org.junit.Test as test
 
 class StringBuilderTest {
 
-    test fun stringBuild() {
+    @test fun stringBuild() {
         val s = StringBuilder {
             append("a")
             append(true)
@@ -13,13 +13,13 @@ class StringBuilderTest {
         assertEquals("atrue", s)
     }
 
-    test fun appendMany() {
+    @test fun appendMany() {
         assertEquals("a1", StringBuilder().append("a", "1").toString())
         assertEquals("a1", StringBuilder().append("a", 1).toString())
         assertEquals("a1", StringBuilder().append("a", StringBuilder().append("1")).toString())
     }
 
-    test fun append() {
+    @test fun append() {
         // this test is needed for JS implementation
         assertEquals("em", StringBuilder {
             append("element", 2, 4)