Revert one of the assertion additions in Bug 1110277 patch 3 since it…

… fires, causing orange. r=orange

Example stack, from editor/libeditor/tests/browserscope/test_richtext2.html :

###!!! ASSERTION: should only call on first continuation/ib-sibling: 'nsLayoutUtils::IsFirstContinuationOrIBSplitSibling(this)', file /builds/slave/m-in-l64-d-0000000000000000000/build/src/layout/base/../generic/nsIFrame.h, line 875
#1: AdjustAppendParentForAfterContent [layout/base/nsCSSFrameConstructor.cpp:6059]
#2: nsCSSFrameConstructor::ContentAppended(nsIContent*, nsIContent*, bool) [layout/base/nsCSSFrameConstructor.cpp:7155]
#03: PresShell::ContentAppended(nsIDocument*, nsIContent*, nsIContent*, int) [layout/base/nsPresShell.cpp:4520]
#04: nsNodeUtils::ContentAppended(nsIContent*, nsIContent*, int) [dom/base/nsNodeUtils.cpp:132]
#05: nsINode::doInsertChildAt(nsIContent*, unsigned int, bool, nsAttrAndChildArray&) [dom/base/nsINode.cpp:1544]
#06: nsINode::ReplaceOrInsertBefore(bool, nsINode*, nsINode*, mozilla::ErrorResult&) [dom/base/nsINode.cpp:2209]
#07: mozilla::dom::NodeBinding::appendChild [obj-firefox/dom/bindings/NodeBinding.cpp:600]

UltraBlame original commit: 98e34be1fb44344c1173d9d3c981b3e5a2da4762

layout/generic/nsIFrame.h

@@ -871,8 +871,6 @@ class nsIFrame : public nsQueryFrame
   NS_DECLARE_FRAME_PROPERTY(GenConProperty, DestroyContentArray)
 
   nsTArray<nsIContent*>* GetGenConPseudos() {
-    NS_ASSERTION(nsLayoutUtils::IsFirstContinuationOrIBSplitSibling(this),
-                 "should only call on first continuation/ib-sibling");
     const FramePropertyDescriptor* prop = GenConProperty();
     return static_cast<nsTArray<nsIContent*>*>(Properties().Get(prop));
   }