Bug 494655 - Refresh flexible space icon on OS X; r=dao

toolkit/themes/pinstripe/global/jar.mn

@@ -161,7 +161,7 @@ classic.jar:
 +  skin/classic/global/splitter/grip-vrt-after.gif                    (splitter/grip-vrt-after.gif)
 +  skin/classic/global/splitter/grip-vrt-before.gif                   (splitter/grip-vrt-before.gif)
 +  skin/classic/global/toolbar/dropmark-nav.png                       (toolbar/dropmark-nav.png)
-+  skin/classic/global/toolbar/spring.gif                             (toolbar/spring.gif)
++  skin/classic/global/toolbar/spring.png                             (toolbar/spring.png)
 +  skin/classic/global/toolbar/toolbar-background.gif                 (toolbar/toolbar-background.gif)
 +  skin/classic/global/toolbar/toolbar-background-inactive.png        (toolbar/toolbar-background-inactive.png)
 +  skin/classic/global/toolbar/toolbar-background-tall.png            (toolbar/toolbar-background-tall.png)

toolkit/themes/pinstripe/global/toolbar.css

@@ -109,7 +109,7 @@ toolbarpaletteitem[type="spacer"] {
 
 .toolbarpaletteitem-box[type="spring"] {
   border: 1px solid #A3A3A3;
-  background: url("chrome://global/skin/toolbar/spring.gif") #FFFFFF no-repeat;
+  background: url("chrome://global/skin/toolbar/spring.png") #FFFFFF no-repeat;
   width: 32px;
   margin-top: 18px;
 }