Fix javascript error in IE9 when loading form with placeholders into an iframe (#1489008)

CHANGELOG

@@ -1,6 +1,7 @@
 CHANGELOG Roundcube Webmail
 ===========================
 
+- Fix javascript error in IE9 when loading form with placeholders into an iframe (#1489008)
 - Fix handling of some conditional comment tags in HTML message (#1489004)
 - Add rel="noreferrer" for links in displayed messages (#1484686)
 - Fix so forward as attachment works if additional attachment is added by message_compose hook (#1489000)

program/js/common.js

@@ -720,10 +720,12 @@ jQuery.fn.placeholder = function(text) {
     var elem = $(this);
     this.title = text;
 
+    // Try HTML5 placeholder attribute first
     if ('placeholder' in this) {
-      elem.attr('placeholder', text);  // Try HTML5 placeholder attribute first
+      elem.attr('placeholder', text);
     }
-    else {  // Fallback to Javascript emulation of placeholder
+    // Fallback to Javascript emulation of placeholder
+    else {
       this._placeholder = text;
       elem.blur(function(e) {
         if ($.trim(elem.val()) == "")
@@ -740,8 +742,13 @@ jQuery.fn.placeholder = function(text) {
         elem[(active ? 'addClass' : 'removeClass')]('placeholder').attr('spellcheck', active);
       });
 
-      if (this != document.activeElement) // Do not blur currently focused element
+      // Do not blur currently focused element
-        elem.blur();
+      // Catch "unspecified error" in IE9 (#1489008)
+      try {
+        if (this != document.activeElement)
+          elem.blur();
+      }
+      catch(e) {}
     }
   });
 };