--- a/dom/webidl/SVGDocument.webidl
+++ b/dom/webidl/SVGDocument.webidl
@@ -5,11 +5,11 @@
  *
  * The origin of this IDL file is:
  * dom/interfaces/svg/nsIDOMSVGDocument.idl
  */
 
 interface SVGDocument : Document {
   [Throws]
   readonly attribute DOMString domain;
-  [Throws]
+  [Pure, Throws]
   readonly attribute SVGElement? rootElement;
 };

--- a/dom/webidl/SVGPathSeg.webidl
+++ b/dom/webidl/SVGPathSeg.webidl
@@ -29,17 +29,19 @@ interface SVGPathSeg {
   const unsigned short PATHSEG_LINETO_HORIZONTAL_REL = 13;
   const unsigned short PATHSEG_LINETO_VERTICAL_ABS = 14;
   const unsigned short PATHSEG_LINETO_VERTICAL_REL = 15;
   const unsigned short PATHSEG_CURVETO_CUBIC_SMOOTH_ABS = 16;
   const unsigned short PATHSEG_CURVETO_CUBIC_SMOOTH_REL = 17;
   const unsigned short PATHSEG_CURVETO_QUADRATIC_SMOOTH_ABS = 18;
   const unsigned short PATHSEG_CURVETO_QUADRATIC_SMOOTH_REL = 19;
 
+  [Pure]
   readonly attribute unsigned short pathSegType;
+  [Pure]
   readonly attribute DOMString pathSegTypeAsLetter;
 };
 
 interface SVGPathSegClosePath : SVGPathSeg {
 };
 
 interface SVGPathSegMovetoAbs : SVGPathSeg {
   [SetterThrows]