Bug 901955 - Get 'opacity' property changes on SVG working again. r=roc

layout/reftests/svg/dynamic-opacity-property-01.svg

@@ -0,0 +1,25 @@
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<svg xmlns="http://www.w3.org/2000/svg" class="reftest-wait">
+
+  <title>Test repainting for opacity property changes</title>
+
+  <script>
+
+function doTest() {
+  document.getElementById("r").style.opacity = 1;
+  document.documentElement.removeAttribute("class");
+}
+
+document.addEventListener("MozReftestInvalidate", doTest, false);
+setTimeout(doTest, 4000); // fallback for running outside reftest
+
+  </script>
+
+  <rect width="100%" height="100%" fill="lime"/>
+  <rect width="100" height="100" fill="red"/>
+  <rect id="r" width="100" height="100" fill="lime" style="opacity:0.5"/>
+
+</svg>

layout/reftests/svg/reftest.list

@@ -89,6 +89,7 @@ skip-if(B2G) == dynamic-marker-02.svg dynamic-marker-02-ref.svg
 skip-if(B2G) == dynamic-marker-03.svg pass.svg
 == dynamic-mask-01.svg pass.svg
 skip-if(B2G) == dynamic-mask-contents-01.svg pass.svg
+== dynamic-opacity-property-01.svg pass.svg
 skip-if(B2G) == dynamic-pattern-01.svg pass.svg
 skip-if(B2G) == dynamic-pattern-02.svg pass.svg
 skip-if(B2G) == dynamic-pattern-contents-01.svg pass.svg

layout/svg/nsSVGPathGeometryFrame.cpp

@@ -120,6 +120,23 @@ nsSVGPathGeometryFrame::AttributeChanged(int32_t         aNameSpaceID,
   return NS_OK;
 }
 
+/* virtual */ void
+nsSVGPathGeometryFrame::DidSetStyleContext(nsStyleContext* aOldStyleContext)
+{
+  nsSVGPathGeometryFrameBase::DidSetStyleContext(aOldStyleContext);
+
+  if (aOldStyleContext) {
+    float oldOpacity = aOldStyleContext->PeekStyleDisplay()->mOpacity;
+    float newOpacity = StyleDisplay()->mOpacity;
+    if (newOpacity != oldOpacity &&
+        nsSVGUtils::CanOptimizeOpacity(this)) {
+      // nsIFrame::BuildDisplayListForStackingContext() is not going to create an
+      // nsDisplayOpacity display list item, so DLBI won't invalidate for us.
+      InvalidateFrame();
+    }
+  }
+}
+
 nsIAtom *
 nsSVGPathGeometryFrame::GetType() const
 {

layout/svg/nsSVGPathGeometryFrame.h

@@ -56,6 +56,8 @@ public:
                                nsIAtom*        aAttribute,
                                int32_t         aModType) MOZ_OVERRIDE;
 
+  virtual void DidSetStyleContext(nsStyleContext* aOldStyleContext);
+
   /**
    * Get the "type" of the frame
    *