Revert "support SSR for addClasses()"

This reverts commit 6d86656.

Author: sanity

.gitignore

@@ -256,29 +256,19 @@ open class Element(
      */
     fun addClasses(vararg classes: String, onlyIf: Boolean = true): Element {
         if (onlyIf) {
-            val jsoupDoc = browser.htmlDocument.get()
-            when {
-                jsoupDoc != null && (browser.isCatchingOutbound() == null || browser.isCatchingOutbound() == RENDER) -> {
-                    val thisEl = jsoupDoc.getElementById(this.id)!!
-                    val existingClasses = thisEl.attr("class").split(" ")
-                    val newClasses = existingClasses + classes
-                    thisEl.attr("class", newClasses.joinToString(separator = " "))
-            } 
-            else -> {
-                for (class_ in classes) {
-                    if (class_.contains(' ')) {
-                        error("Class names must not contain spaces")
-                    }
-                    //language=JavaScript
-                    callJsFunction("""
-                        let id = {};
-                        let className = {};
-                        let el = document.getElementById(id);
-                        if (el.classList) el.classList.add(className);
-                        else if (!hasClass(el, className)) el.className += " " + className;
-                    """.trimIndent(), id.json, JsonPrimitive(class_))
+            for (class_ in classes) {
+                if (class_.contains(' ')) {
+                    error("Class names must not contain spaces")
                 }
-        }
+                //language=JavaScript
+                callJsFunction("""
+                    let id = {};
+                    let className = {};
+                    let el = document.getElementById(id);
+                    if (el.classList) el.classList.add(className);
+                    else if (!hasClass(el, className)) el.className += " " + className;
+                """.trimIndent(), id.json, JsonPrimitive(class_))
+            }
         }
         return this
     }