--- a/layout/svg/nsSVGIntegrationUtils.cpp
+++ b/layout/svg/nsSVGIntegrationUtils.cpp
@@ -718,16 +718,42 @@ nsSVGIntegrationUtils::DetermineMaskUsag
                  !aUsage.shouldApplyClipPath && !aUsage.shouldApplyBasicShape);
       break;
     default:
       MOZ_ASSERT_UNREACHABLE("Unsupported clip-path type.");
       break;
   }
 }
 
+bool
+nsSVGIntegrationUtils::IsMaskResourceReady(nsIFrame* aFrame)
+{
+  nsIFrame* firstFrame =
+    nsLayoutUtils::FirstContinuationOrIBSplitSibling(aFrame);
+  nsSVGEffects::EffectProperties effectProperties =
+    nsSVGEffects::GetEffectProperties(firstFrame);
+  nsTArray<nsSVGMaskFrame*> maskFrames = effectProperties.GetMaskFrames();
+  const nsStyleSVGReset* svgReset = firstFrame->StyleSVGReset();
+
+  for (uint32_t i = 0; i < maskFrames.Length(); i++) {
+    // Refers to a valid SVG mask.
+    if (maskFrames[i]) {
+      continue;
+    }
+
+    // Refers to an external resource, which is not ready yet.
+    if (!svgReset->mMask.mLayers[i].mImage.IsComplete()) {
+      return false;
+    }
+  }
+
+  // Either all mask resources are ready, or no mask resource is needed.
+  return true;
+}
+
 DrawResult
 nsSVGIntegrationUtils::PaintMaskAndClipPath(const PaintFramesParams& aParams)
 {
   MOZ_ASSERT(UsingMaskOrClipPathForFrame(aParams.frame),
              "Should not use this method when no mask or clipPath effect"
              "on this frame");
 
   /* SVG defines the following rendering model:

--- a/layout/svg/nsSVGIntegrationUtils.h
+++ b/layout/svg/nsSVGIntegrationUtils.h
@@ -172,16 +172,22 @@ public:
         shouldApplyClipPath(false), shouldApplyBasicShape(false), opacity(0.0)
     { }
   };
 
   static void
   DetermineMaskUsage(nsIFrame* aFrame, bool aHandleOpacity, MaskUsage& aUsage);
 
   /**
+   * Return true if all the mask resource of aFrame are ready.
+   */
+  static bool
+  IsMaskResourceReady(nsIFrame* aFrame);
+
+  /**
    * Paint non-SVG frame with filter and opacity effect.
    */
   static DrawResult
   PaintFilter(const PaintFramesParams& aParams);
 
   /**
    * SVG frames expect to paint in SVG user units, which are equal to CSS px
    * units. This method provides a transform matrix to multiply onto a