Bug 1388832 - Fix right-click on searchbar when in overflow menu. r=jaws

* Swap margins for paddings around the searchbar when in a menu. Elements that could precede and follow the searchbar all have margin: 0, and define top/bottom padding as 4px, so this seems reasonable
* Replace the loop that looks for an appropriate trigger node to use element.closest. A click on the outside a toolbarbutton/item was climbing to the document node and throwing as it has no getAttribute method.

MozReview-Commit-ID: LuniL3gdLWR

--HG--
extra : rebase_source : b6f6cfa84b0d388c63bb3feea71100a38e26bb60

browser/base/content/browser.js

@@ -5428,15 +5428,8 @@ function onViewToolbarsPopupShowing(aEvent, aInsertPoint) {
   if (toolbarItem && toolbarItem.localName == "toolbarpaletteitem") {
     toolbarItem = toolbarItem.firstChild;
   } else if (toolbarItem && toolbarItem.localName != "toolbar") {
-    while (toolbarItem && toolbarItem.parentNode) {
-      let parent = toolbarItem.parentNode;
-      if ((parent.classList && parent.classList.contains("customization-target")) ||
-          parent.getAttribute("overflowfortoolbar") || // Needs to work in the overflow list as well.
-          parent.localName == "toolbarpaletteitem" ||
-          parent.localName == "toolbar")
-        break;
-      toolbarItem = parent;
-    }
+    toolbarItem = toolbarItem.closest(
+      ".customization-target, [overflowfortoolbar], toolbarpaletteitem, toolbar");
   } else {
     toolbarItem = null;
   }

browser/themes/shared/customizableui/panelUI.inc.css

@@ -1622,8 +1622,8 @@ toolbarpaletteitem[place="palette"] > .toolbarbutton-1 > .toolbarbutton-menubutt
 }
 
 #search-container[cui-areatype="menu-panel"] {
-  margin-top: 6px;
-  margin-bottom: 6px;
+  padding-top: 6px;
+  padding-bottom: 6px;
 }
 
 toolbarpaletteitem[place="palette"] > #search-container {