Bug 1294171 - Part 1. Treat unresolvable mask as no mask before support image mask. r=mstange

MozReview-Commit-ID: 9f2k7NtpYuR

--HG--
extra : rebase_source : b39ef5f82382fd9d7f237d1dabd6d834b8bbefa0

layout/svg/nsSVGIntegrationUtils.cpp

@@ -697,6 +697,8 @@ nsSVGIntegrationUtils::PaintFramesWithEffects(const PaintFramesParams& aParams)
 
   const nsStyleSVGReset *svgReset = firstFrame->StyleSVGReset();
   nsTArray<nsSVGMaskFrame *> maskFrames = effectProperties.GetMaskFrames();
+
+#ifdef MOZ_ENABLE_MASK_AS_SHORTHAND
   // For a HTML doc:
   //   According to css-masking spec, always create a mask surface when we
   //   have any item in maskFrame even if all of those items are
@@ -708,6 +710,13 @@ nsSVGIntegrationUtils::PaintFramesWithEffects(const PaintFramesParams& aParams)
   bool shouldGenerateMaskLayer = hasSVGLayout
                                  ? maskFrames.Length() == 1 && maskFrames[0]
                                  : maskFrames.Length() > 0;
+#else
+  // Since we do not support image mask so far, we should treat any
+  // unresolvable mask as no mask. Otherwise, any object with a valid image
+  // mask, e.g. url("xxx.png"), will become invisible just because we can not
+  // handle image mask correctly. (See bug 1294171)
+  bool shouldGenerateMaskLayer = maskFrames.Length() == 1 && maskFrames[0];
+#endif
 
   // These are used if we require a temporary surface for a custom blend mode.
   RefPtr<gfxContext> target = &aParams.ctx;