bug 136746 - check for null pointer if a line is empty. sr=waterson, r=alexsavulov

git-svn-id: svn://10.0.0.236/trunk@119857 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/layout/generic/nsBlockFrame.cpp

@@ -3113,6 +3113,10 @@ nsBlockFrame::ReflowBlockFrame(nsBlockReflowState& aState,
   nsresult rv = NS_OK;
 
   nsIFrame* frame = aLine->mFirstChild;
+  if (!frame) {
+    NS_ASSERTION(PR_FALSE, "program error - unexpected empty line"); 
+    return NS_ERROR_NULL_POINTER; 
+  }
 
   // Prepare the block reflow engine
   const nsStyleDisplay* display;