workaround for IE when manipulating classes. fixes select2#937 fixes select2#1017

Author: ivaynberg

select2.js

@@ -284,19 +284,21 @@ the specific language governing permissions and limitations under the Apache Lic
         var classes, replacements = [], adapted;
 
         classes = dest.attr("class");
-        if (typeof classes === "string") {
+        if (classes) {
+            classes = '' + classes; // for IE which returns object
             $(classes.split(" ")).each2(function() {
                 if (this.indexOf("select2-") === 0) {
                     replacements.push(this);
                 }
             });
         }
         classes = src.attr("class");
-        if (typeof classes === "string") {
+        if (classes) {
+            classes = '' + classes; // for IE which returns object
             $(classes.split(" ")).each2(function() {
                 if (this.indexOf("select2-") !== 0) {
                     adapted = adapter(this);
-                    if (typeof adapted === "string" && adapted.length > 0) {
+                    if (adapted) {
                         replacements.push(this);
                     }
                 }