Bug 1521040 - Remove ondialoghelp attribute and add custom event handler r=Gijs

Differential Revision: https://phabricator.services.mozilla.com/D16946

--HG--
extra : moz-landing-system : lando

browser/base/content/utilityOverlay.js

@@ -973,6 +973,8 @@ function openHelpLink(aHelpTopic, aCalledFromModal, aWhere) {
   openTrustedLinkIn(url, where);
 }
 
+window.addEventListener("dialoghelp", openPrefsHelp);
+
 function openPrefsHelp() {
   // non-instant apply prefwindows are usually modal, so we can't open in the topmost window,
   // since its probably behind the window.

browser/components/preferences/browserLanguages.xul

@@ -16,8 +16,7 @@
         role="dialog"
         onload="gBrowserLanguagesDialog.onLoad();"
         onbeforeaccept="return gBrowserLanguagesDialog.beforeAccept();"
-        helpTopic="prefs-languages"
-        ondialoghelp="openPrefsHelp()">
+        helpTopic="prefs-languages">
 
   <linkset>
     <link rel="localization" href="branding/brand.ftl"/>

browser/components/preferences/colors.xul

@@ -16,8 +16,7 @@
         buttons="accept,cancel,help"
         persist="lastSelected screenX screenY"
         role="dialog"
-        helpTopic="prefs-fonts-and-colors"
-        ondialoghelp="openPrefsHelp()">
+        helpTopic="prefs-fonts-and-colors">
 
   <linkset>
     <link rel="localization" href="browser/preferences/colors.ftl"/>

browser/components/preferences/connection.xul

@@ -17,8 +17,7 @@
         role="dialog"
         onbeforeaccept="return gConnectionsDialog.beforeAccept();"
         onload="gConnectionsDialog.checkForSystemProxy();"
-        helpTopic="prefs-connection-settings"
-        ondialoghelp="openPrefsHelp()">
+        helpTopic="prefs-connection-settings">
 
   <!-- Used for extension-controlled lockdown message -->
   <linkset>

browser/components/preferences/fonts.xul

@@ -16,8 +16,7 @@
         buttons="accept,cancel,help"
         persist="lastSelected screenX screenY"
         role="dialog"
-        helpTopic="prefs-fonts-and-colors"
-        ondialoghelp="openPrefsHelp()">
+        helpTopic="prefs-fonts-and-colors">
 
   <linkset>
     <link rel="localization" href="browser/preferences/fonts.ftl"/>

browser/components/preferences/languages.xul

@@ -15,8 +15,7 @@
         persist="lastSelected screenX screenY"
         role="dialog"
         onload="gLanguagesDialog.onLoad();"
-        helpTopic="prefs-languages"
-        ondialoghelp="openPrefsHelp()">
+        helpTopic="prefs-languages">
 
   <linkset>
     <link rel="localization" href="browser/preferences/languages.ftl"/>

browser/components/preferences/sanitize.xul

@@ -16,7 +16,6 @@
         buttons="accept,cancel,help"
         persist="lastSelected screenX screenY"
         role="dialog"
-        ondialoghelp="openPrefsHelp()"
         data-l10n-id="sanitize-prefs"
         data-l10n-attrs="style"
         helpTopic="prefs-clear-private-data"