Bug 289910 - area invalidation not correct if new style resulted

in an empty region. r=afri, a=asa

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

@@ -362,21 +362,24 @@ nsSVGCairoGlyphGeometry::Update(PRUint32 updatemask, nsISVGRendererRegion **_ret
     nsISVGGlyphGeometrySource::UPDATEMASK_Y       |
     nsISVGGeometrySource::UPDATEMASK_CANVAS_TM;
 
+  nsCOMPtr<nsISVGRendererRegion> before = mCoveredRegion;
+
   if ((updatemask & regionsmask) || (updatemask & strokemask)) {
     nsCOMPtr<nsISVGRendererRegion> after;
     GetCoveredRegion(getter_AddRefs(after));
 
     if (mCoveredRegion) {
       if (after)
-        after->Combine(mCoveredRegion, _retval);
+        after->Combine(before, _retval);
     } else {
       *_retval = after;
       NS_IF_ADDREF(*_retval);
     }
     mCoveredRegion = after;
   }
-  else if (updatemask != nsISVGGeometrySource::UPDATEMASK_NOTHING) {
-    *_retval = mCoveredRegion;
+
+  if (!*_retval) {
+    *_retval = before;
     NS_IF_ADDREF(*_retval);
   }
 

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

@@ -389,21 +389,24 @@ nsSVGCairoPathGeometry::Update(PRUint32 updatemask, nsISVGRendererRegion **_retv
     nsISVGGeometrySource::UPDATEMASK_FILL_PAINT_TYPE    |
     nsISVGGeometrySource::UPDATEMASK_STROKE_PAINT_TYPE;
 
+  nsCOMPtr<nsISVGRendererRegion> before = mCoveredRegion;
+
   if (updatemask & coveredregionmask) {
     nsCOMPtr<nsISVGRendererRegion> after;
     GetCoveredRegion(getter_AddRefs(after));
 
     if (mCoveredRegion) {
       if (after)
-        after->Combine(mCoveredRegion, _retval);
+        after->Combine(before, _retval);
     } else {
       *_retval = after;
       NS_IF_ADDREF(*_retval);
     }
     mCoveredRegion = after;
   }
-  else if (updatemask != nsISVGGeometrySource::UPDATEMASK_NOTHING) {
-    *_retval = mCoveredRegion;
+
+  if (!*_retval) {
+    *_retval = before;
     NS_IF_ADDREF(*_retval);
   }
 

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

@@ -524,9 +524,10 @@ nsSVGGDIPlusGlyphGeometry::Update(PRUint32 updatemask, nsISVGRendererRegion **_r
       NS_IF_ADDREF(*_retval);
     }
   }
-  else if (updatemask != nsISVGGeometrySource::UPDATEMASK_NOTHING) {
+
+  if (!*_retval) {
     // region hasn't changed, but something has. so invalidate whole area:
-    *_retval = mCoveredRegion;
+    *_retval = regionBefore;
     NS_IF_ADDREF(*_retval);
   }    
       

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

@@ -530,7 +530,8 @@ nsSVGGDIPlusPathGeometry::Update(PRUint32 updatemask, nsISVGRendererRegion **_re
     if (after)
       after->Combine(before, _retval);
   }
-  else if (updatemask != nsISVGGeometrySource::UPDATEMASK_NOTHING) {
+
+  if (!*_retval) {
     *_retval = before;
     NS_IF_ADDREF(*_retval);
   }

layout/svg/renderer/src/libart/nsSVGLibartPathGeometry.cpp

@@ -395,7 +395,8 @@ nsSVGLibartPathGeometry::Update(PRUint32 updatemask, nsISVGRendererRegion **_ret
     if (after)
       after->Combine(before, _retval);
   }
-  else if (updatemask != nsISVGGeometrySource::UPDATEMASK_NOTHING) {
+
+  if (!*_retval) {
     *_retval = before;
     NS_IF_ADDREF(*_retval);
   }