Bug 1381321: Support <select> dropdowns in OOP options browsers. r=aswan

MozReview-Commit-ID: 1hYgY7s0a6V

--HG--
extra : rebase_source : 78f568dbdeb3dcb0500913648d3c9bfbdfffd138

toolkit/content/xul.css

@@ -1015,6 +1015,7 @@ menulist[popuponly="true"] {
   -moz-appearance: none !important;
   margin: 0 !important;
   height: 0 !important;
+  min-height: 0 !important;
   border: 0 !important;
 }
 

toolkit/mozapps/extensions/content/extensions.js

@@ -3714,6 +3714,7 @@ var gDetailView = {
     browser.setAttribute("id", "addon-options");
     browser.setAttribute("class", "inline-options-browser");
     browser.setAttribute("forcemessagemanager", "true");
+    browser.setAttribute("selectmenulist", "ContentSelectDropdown");
 
     let {optionsURL} = this._addon;
     let remote = !E10SUtils.canLoadURIInProcess(optionsURL, Services.appinfo.PROCESS_TYPE_DEFAULT);

toolkit/mozapps/extensions/content/extensions.xul

@@ -69,6 +69,16 @@
                 accesskey="&cmd.about.accesskey;"/>
     </menupopup>
 
+    <menulist popuponly="true" id="ContentSelectDropdown" hidden="true">
+      <menupopup rolluponmousewheel="true"
+                 activateontab="true" position="after_start"
+                 level="parent"
+#ifdef XP_WIN
+                 consumeoutsideclicks="false" ignorekeys="shortcuts"
+#endif
+        />
+    </menulist>
+
     <tooltip id="addonitem-tooltip"/>
   </popupset>