Bug 618205 - SVG SMIL: Correctly fallback to non-additive animation on display and shorthand properties; r=dholbert; a=roc

content/smil/nsSMILCSSProperty.cpp

@@ -113,10 +113,10 @@ nsSMILCSSProperty::GetBaseValue() const
     // doing so involves clearing and resetting the property which can cause
     // frames to be recreated which we'd like to avoid.
     //
-    // In either case, simply returning a null-typed nsSMILValue to indicate
-    // failure is acceptable because the caller only uses base values when
-    // there's interpolation or addition, and for both the shorthand properties
-    // we know about and the display property those operations aren't supported.
+    // In either case, just return a dummy value (initialized with the right
+    // type, so as not to indicate failure).
+    nsSMILValue tmpVal(&nsSMILCSSValueType::sSingleton);
+    baseValue.Swap(tmpVal);
     return baseValue;
   }
 

layout/reftests/svg/smil/anim-additive-fallback-1.svg

@@ -0,0 +1,14 @@
+<svg xmlns="http://www.w3.org/2000/svg"
+     xmlns:xlink="http://www.w3.org/1999/xlink"
+     class="reftest-wait"
+     onload="setTimeAndSnapshot(0.5, true)">
+  <script xlink:href="smil-util.js" type="text/javascript"/>
+  <rect x="15" y="15" width="200" height="200" fill="blue" display="none">
+    <!-- The following animation is marked as additive even though the display
+         property is not additive. We should basically behave as if the additive
+         attribute were not specified and set display to 'block' after 0.5s.
+         -->
+    <animate attributeName="display" from="none" to="block" additive="sum"
+      dur="1s" fill="freeze"/>
+  </rect>
+</svg>

layout/reftests/svg/smil/reftest.list

@@ -134,6 +134,9 @@ asserts(9) == anim-use-href-01.svg lime.svg  # the asserts here are bug 563481
 == anim-fill-overpaintserver-1.svg lime.svg
 == anim-fill-overpaintserver-2.svg lime.svg
 
+# animate where we fallback from 'additive' animation to non-additive
+== anim-additive-fallback-1.svg anim-standard-ref.svg
+
 == anim-remove-1.svg anim-standard-ref.svg
 == anim-remove-2.svg anim-standard-ref.svg
 == anim-remove-3.svg anim-standard-ref.svg