Bug 1451256: Remove extends from toolbarpalleteitem. r=dao

Right now it uses extends="xul:button" so that the element it wraps doesn't get
mouse events. There's a way to do that with CSS, using pointer-events: none on
the child.

MozReview-Commit-ID: 29QZAoJPFt6

--HG--
extra : rebase_source : a23406b2c5bc9a6ca8d4a926b4867bc451cada8d

toolkit/content/widgets/toolbar.xml

@@ -169,7 +169,7 @@
     </handlers>
   </binding>
 
-  <binding id="toolbarpaletteitem" extends="xul:button">
+  <binding id="toolbarpaletteitem">
     <content>
       <xul:hbox class="toolbarpaletteitem-box" flex="1" xbl:inherits="type,place">
         <children/>

toolkit/content/xul.css

@@ -321,6 +321,11 @@ toolbarpaletteitem[place="palette"] {
   -moz-binding: url("chrome://global/content/bindings/toolbar.xml#toolbarpaletteitem-palette");
 }
 
+.toolbarpaletteitem-box {
+  /* Prevent children from getting events */
+  pointer-events: none;
+}
+
 /********* menubar ***********/
 
 menubar {