Bug 641942 - Make Windows progress bars RTL-friendly. r=jimm

widget/src/windows/nsNativeThemeWin.cpp

@@ -1600,6 +1600,11 @@ RENDER_AGAIN:
       double tempValue;
       double ratio = modf(PR_IntervalToMilliseconds(PR_IntervalNow())/interval,
                           &tempValue);
+      // If the frame direction is RTL, we want to have the animation going RTL.
+      // ratio is in [0.0; 1.0[ range, inverting it reverse the animation.
+      if (IsFrameRTL(aFrame)) {
+        ratio = 1.0 - ratio;
+      }
       PRInt32 dx = static_cast<PRInt32>(animationWidth * ratio) - overlayWidth;
 
       RECT overlayRect = widgetRect;