Remove legacy browser check for DOMContentLoaded

Author: LakshyaBagani

core/src/main/resources/lib/hudson/project/configurable.jelly

@@ -29,7 +29,8 @@ THE SOFTWARE.
 
     <j:if test="${!newJobPage}">
       <j:if test="${it.buildable}">
-        <l:task href="${url}/build?delay=0sec" icon="icon-clock icon-md" permission="${it.BUILD}" post="${!it.parameterized}" data-task-failure="${%buildFailed}" data-task-success="${%Build scheduled}" title="${it.buildNowText}"/>
+        <st:adjunct includes="lib.hudson.project.configurable.configurable"/>
+        <l:task href="${url}/build?delay=0sec" icon="icon-clock icon-md" permission="${it.BUILD}" post="${!it.parameterized}" data-callback="lib_hudson_project_configurable_build_now_callback" data-build-failure="${%buildFailed}" data-build-success="${%Build scheduled}" data-parameterized="${it.parameterized}" title="${it.buildNowText}"/>
       </j:if>
       <j:choose>
         <j:when test="${h.hasPermission(it,it.CONFIGURE)}">

war/src/main/webapp/scripts/behavior.js

@@ -81,15 +81,9 @@ var Behaviour = (function () {
     },
 
     start: function () {
-      if (document.addEventListener) {
-        document.addEventListener("DOMContentLoaded", function () {
-          Behaviour.apply();
-        });
-      } else {
-        Behaviour.addLoadEvent(function () {
-          Behaviour.apply();
-        });
-      }
+      document.addEventListener("DOMContentLoaded", function () {
+        Behaviour.apply();
+      });
     },
 
     apply: function () {