Bug 898915 - Fix Axis() is not valid abort. r=dholbert

content/svg/content/src/SVGLengthListSMILType.cpp

@@ -93,12 +93,6 @@ SVGLengthListSMILType::Add(nsSMILValue& aDest,
   // should be, not zeros, and those values are not explicit or otherwise
   // available.
 
-  if (dest.IsEmpty() && valueToAdd.IsEmpty()) {
-    // Adding two identity values, no-op.  This occurs when performing a
-    // discrete by-animation on an attribute with no specified base value.
-    return NS_OK;
-  }
-
   if (!valueToAdd.Element()) { // Adding identity value - no-op
     NS_ABORT_IF_FALSE(valueToAdd.IsEmpty(),
                       "Identity values should be empty");

content/svg/content/src/crashtests/898915-1.svg

@@ -0,0 +1,5 @@
+<svg xmlns="http://www.w3.org/2000/svg">
+  <text>
+    <animate attributeName="y" by="" />
+  </text>
+</svg>

content/svg/content/src/crashtests/crashtests.list

@@ -71,3 +71,4 @@ load 880544-2.svg
 load 880544-3.svg
 load 880544-4.svg
 load 880544-5.svg
+load 898915-1.svg