Bug 852501 part 17. Make ConstructRootFrame infallible. r=dholbert

layout/base/nsCSSFrameConstructor.cpp

@@ -2500,11 +2500,10 @@ nsCSSFrameConstructor::ConstructDocElementFrame(Element*                 aDocEle
 }
 
 
-nsresult
-nsCSSFrameConstructor::ConstructRootFrame(nsIFrame** aNewFrame)
+nsIFrame*
+nsCSSFrameConstructor::ConstructRootFrame()
 {
   AUTO_LAYOUT_PHASE_ENTRY_POINT(mPresShell->GetPresContext(), FrameC);
-  NS_PRECONDITION(aNewFrame, "null out param");
 
   nsStyleSet *styleSet = mPresShell->StyleSet();
 
@@ -2543,8 +2542,7 @@ nsCSSFrameConstructor::ConstructRootFrame(nsIFrame** aNewFrame)
   mFixedContainingBlock->AddStateBits(NS_FRAME_CAN_HAVE_ABSPOS_CHILDREN);
   mFixedContainingBlock->MarkAsAbsoluteContainingBlock();
 
-  *aNewFrame = viewportFrame;
-  return NS_OK;
+  return viewportFrame;
 }
 
 nsresult

layout/base/nsCSSFrameConstructor.h

@@ -73,8 +73,7 @@ private:
   nsCSSFrameConstructor& operator=(const nsCSSFrameConstructor& aCopy) MOZ_DELETE;
 
 public:
-  // XXXbz this method needs to actually return errors!
-  nsresult ConstructRootFrame(nsIFrame** aNewFrame);
+  nsIFrame* ConstructRootFrame();
 
   nsresult ReconstructDocElementHierarchy();
 

layout/base/nsPresShell.cpp

@@ -1701,7 +1701,7 @@ PresShell::Initialize(nscoord aWidth, nscoord aHeight)
   if (!rootFrame) {
     nsAutoScriptBlocker scriptBlocker;
     mFrameConstructor->BeginUpdate();
-    mFrameConstructor->ConstructRootFrame(&rootFrame);
+    rootFrame = mFrameConstructor->ConstructRootFrame();
     mFrameConstructor->SetRootFrame(rootFrame);
     mFrameConstructor->EndUpdate();
   }