try: -b do -p linux,linux64,macosx,macosx64,win32 -u all -t none

diff --git a/browser/base/content/tabbrowser.xml b/browser/base/content/tabbrowser.xml
--- a/browser/base/content/tabbrowser.xml
+++ b/browser/base/content/tabbrowser.xml
@@ -1226,15 +1226,6 @@
 
             this.tabContainer.appendChild(t);
 
-            if (this.tabContainer.mTabstrip._isRTLScrollbox) {
-              /* In RTL UI, the tab is visually added to the left side of the
-               * tabstrip. This means the tabstip has to be scrolled back in
-               * order to make sure the same set of tabs is visible before and
-               * after the new tab is added.  See bug 508816. */
-
-              this.tabContainer.mTabstrip.scrollByPixels(t.clientWidth);
-            }
-
             // invalidate cache, because tabContainer is about to change
             this._browsers = null;
 
diff --git a/browser/components/places/content/browserPlacesViews.js b/browser/components/places/content/browserPlacesViews.js
--- a/browser/components/places/content/browserPlacesViews.js
+++ b/browser/components/places/content/browserPlacesViews.js
@@ -1035,11 +1035,6 @@ PlacesToolbar.prototype = {
     if (this._chevron.collapsed)
       return;
 
-    // XXX (bug 508816) Scrollbox does not handle correctly RTL mode.
-    // This workarounds the issue scrolling the box to the right.
-    if (this.isRTL)
-      this._rootElt.scrollLeft = this._rootElt.scrollWidth;
-
     // Update the chevron on a timer.  This will avoid repeated work when
     // lot of changes happen in a small timeframe.
     if (this._updateChevronTimer)
diff --git a/toolkit/content/widgets/scrollbox.xml b/toolkit/content/widgets/scrollbox.xml
--- a/toolkit/content/widgets/scrollbox.xml
+++ b/toolkit/content/widgets/scrollbox.xml
@@ -143,9 +143,15 @@
           // This assumes that this._scrollbox doesn't have any border.
           var outerRect = this.scrollClientRect;
           var innerRect = {};
-          innerRect.left = outerRect.left - this._scrollbox.scrollLeft;
+          var ltr = (window.getComputedStyle(this, null).direction == "ltr");
+          if (true || ltr) {
+            innerRect.left = outerRect.left - this._scrollbox.scrollLeft;
+            innerRect.right = innerRect.left + this._scrollbox.scrollWidth;
+          } else {
+            innerRect.right = outerRect.right - this._scrollbox.scrollLeft;
+            innerRect.left = innerRect.right - this._scrollbox.scrollWidth;
+          }
           innerRect.top = outerRect.top - this._scrollbox.scrollTop;
-          innerRect.right = innerRect.left + this._scrollbox.scrollWidth;
           innerRect.bottom = innerRect.top + this._scrollbox.scrollHeight;
           return innerRect;
         ]]></getter>