Add reverse() function to js version of StringBuilder

js/js.libraries/src/core/javalang.kt

@@ -51,5 +51,6 @@ public class StringBuilder() : Appendable {
     //TODO
     //override fun append(csq: CharSequence?, start: Int, end: Int): StringBuilder = js.noImpl
     public fun append(obj: Any?): StringBuilder = js.noImpl
+    public fun reverse(): StringBuilder = js.noImpl
     override fun toString(): String = js.noImpl
 }

js/js.translator/testData/kotlin_lib.js

@@ -603,6 +603,10 @@
             this.string = this.string + obj.toString();
             return this;
         },
+        reverse: function () {
+            this.string = this.string.split("").reverse().join("");
+            return this;
+        },
         toString: function () {
             return this.string;
         }