Bug 310382 - follow svg rule for dealing with out-of-order stops. r=jwatt

layout/svg/renderer/src/cairo/nsSVGCairoGradient.cpp

@@ -66,6 +66,8 @@ static void
 CairoSetStops(cairo_pattern_t *aPattern, nsISVGGradient *aGrad)
 {
   PRUint32 nStops;
+  float lastOffset = 0.0f;
+
   aGrad->GetStopCount(&nStops);
   for (PRUint32 i = 0; i < nStops; i++) {
     nscolor rgba;
@@ -76,6 +78,11 @@ CairoSetStops(cairo_pattern_t *aPattern, nsISVGGradient *aGrad)
     aGrad->GetStopColor(i, &rgba);
     aGrad->GetStopOpacity(i, &opacity);
 
+    if (offset < lastOffset)
+      offset = lastOffset;
+    else
+      lastOffset = offset;
+
     cairo_pattern_add_color_stop_rgba(aPattern, offset,
                                       NS_GET_R(rgba)/255.0,
                                       NS_GET_G(rgba)/255.0,

layout/svg/renderer/src/gdiplus/nsSVGGDIPlusGradient.cpp

@@ -111,6 +111,8 @@ GDIPlusGetStops(nsISVGGradient *aGrad, Color **aColors, REAL **aPositions,
 
     if (offset < lastOffset)
       offset = lastOffset;
+    else
+      lastOffset = offset;
 
     (*aColors)[idx].SetValue(argb);
     (*aPositions)[idx] = (REAL)offset;