Bug 512173 Make message-icon class work on all platforms again r=dao

toolkit/themes/pinstripe/global/global.css

@@ -105,10 +105,7 @@ window.dialog {
 
 /* ::::: alert icons :::::*/
 
-.message-icon {
-  display: none;
-}
-
+.message-icon,
 .alert-icon,
 .error-icon,
 .question-icon {
@@ -118,6 +115,10 @@ window.dialog {
   -moz-margin-end: 20px;
 }
 
+.message-icon {
+  list-style-image: url("chrome://global/skin/icons/information-64.png");
+}
+
 .alert-icon {
   list-style-image: url("chrome://global/skin/icons/warning-64.png");
 }

toolkit/themes/winstripe/global/global.css

@@ -95,7 +95,7 @@ window.dialog {
 }
 
 .message-icon {
-  list-style-image: url("chrome://global/skin/icons/Message.png");
+  list-style-image: url("chrome://global/skin/icons/information-32.png");
 }
 
 .alert-icon {