Migrate UseExperimental->OptIn in project sources

libraries/stdlib/js/src/kotlin/collections/ArraysJs.kt

@@ -6,7 +6,7 @@
 package kotlin.collections
 
 
-@UseExperimental(ExperimentalUnsignedTypes::class)
+@OptIn(ExperimentalUnsignedTypes::class)
 @SinceKotlin("1.3")
 @kotlin.js.JsName("contentDeepHashCodeImpl")
 internal fun <T> Array<out T>.contentDeepHashCodeImpl(): Int {

libraries/stdlib/js/src/kotlin/text/StringBuilderJs.kt

@@ -46,7 +46,7 @@ public actual class StringBuilder actual constructor(content: String) : Appendab
         return this
     }
 
-    @UseExperimental(ExperimentalStdlibApi::class)
+    @OptIn(ExperimentalStdlibApi::class)
     actual override fun append(value: CharSequence?, startIndex: Int, endIndex: Int): StringBuilder = this.appendRange(value, startIndex, endIndex)
 
     /**

libraries/stdlib/js/src/kotlin/text/utf8Encoding.kt

@@ -6,7 +6,7 @@
 package kotlin.text
 
 /** Returns the negative [size] if [throwOnMalformed] is false, throws [CharacterCodingException] otherwise. */
-@UseExperimental(ExperimentalStdlibApi::class)
+@OptIn(ExperimentalStdlibApi::class)
 private fun malformed(size: Int, index: Int, throwOnMalformed: Boolean): Int {
     if (throwOnMalformed) throw CharacterCodingException("Malformed sequence starting at ${index - 1}")
     return -size