Bug 215083: Account for subclasses in the next-in-flow assertion. r=me a=fix-uplift

MozReview-Commit-ID: 2E8Fm4Lxnf8

--HG--
extra : source : c3983769db6d28b2af6f4f7d1dee2f4ed4aa887a
extra : amend_source : 94001c14b0f333814e099fc0a8c57d120bb6feaf

layout/generic/nsImageFrame.cpp

@@ -293,7 +293,7 @@ nsImageFrame::Init(nsIContent* aContent,
                    nsIFrame* aPrevInFlow)
 {
   MOZ_ASSERT_IF(aPrevInFlow,
-                aPrevInFlow->Type() == LayoutFrameType::Image &&
+                aPrevInFlow->Type() == Type() &&
                 static_cast<nsImageFrame*>(aPrevInFlow)->mKind == mKind);
 
   nsAtomicContainerFrame::Init(aContent, aParent, aPrevInFlow);