diff --git a/mozilla/layout/generic/nsHTMLFrame.cpp b/mozilla/layout/generic/nsHTMLFrame.cpp
index 71bd7649a1f..592920a4a9c 100644
--- a/mozilla/layout/generic/nsHTMLFrame.cpp
+++ b/mozilla/layout/generic/nsHTMLFrame.cpp
@@ -272,6 +272,30 @@ RootFrame::Reflow(nsIPresContext&          aPresContext,
     aDesiredSize.ascent = aDesiredSize.height;
     aDesiredSize.descent = 0;
 
+    // Set NS_FRAME_OUTSIDE_CHILDREN flag, or reset it, as appropriate
+    nsFrameState  kidState;
+    kidFrame->GetFrameState(kidState);
+    if (NS_FRAME_OUTSIDE_CHILDREN & kidState) {
+      nscoord kidXMost = kidReflowState.computedMargin.left +
+                         kidDesiredSize.mCombinedArea.XMost();
+      nscoord kidYMost = kidReflowState.computedMargin.top +
+                         kidDesiredSize.mCombinedArea.YMost();
+
+      if ((kidXMost > aDesiredSize.width) || (kidYMost > aDesiredSize.height)) {
+        aDesiredSize.mCombinedArea.x = 0;
+        aDesiredSize.mCombinedArea.y = 0;
+        aDesiredSize.mCombinedArea.width = PR_MAX(aDesiredSize.width, kidXMost);
+        aDesiredSize.mCombinedArea.height = PR_MAX(aDesiredSize.height, kidYMost);
+        mState |= NS_FRAME_OUTSIDE_CHILDREN;
+
+      } else {
+        mState &= ~NS_FRAME_OUTSIDE_CHILDREN;
+      }
+
+    } else {
+      mState &= ~NS_FRAME_OUTSIDE_CHILDREN;
+    }
+
     // XXX Temporary hack. Remember this for later when our parent resizes us
     mNaturalHeight = aDesiredSize.height;
   }
diff --git a/mozilla/layout/html/base/src/nsHTMLFrame.cpp b/mozilla/layout/html/base/src/nsHTMLFrame.cpp
index 71bd7649a1f..592920a4a9c 100644
--- a/mozilla/layout/html/base/src/nsHTMLFrame.cpp
+++ b/mozilla/layout/html/base/src/nsHTMLFrame.cpp
@@ -272,6 +272,30 @@ RootFrame::Reflow(nsIPresContext&          aPresContext,
     aDesiredSize.ascent = aDesiredSize.height;
     aDesiredSize.descent = 0;
 
+    // Set NS_FRAME_OUTSIDE_CHILDREN flag, or reset it, as appropriate
+    nsFrameState  kidState;
+    kidFrame->GetFrameState(kidState);
+    if (NS_FRAME_OUTSIDE_CHILDREN & kidState) {
+      nscoord kidXMost = kidReflowState.computedMargin.left +
+                         kidDesiredSize.mCombinedArea.XMost();
+      nscoord kidYMost = kidReflowState.computedMargin.top +
+                         kidDesiredSize.mCombinedArea.YMost();
+
+      if ((kidXMost > aDesiredSize.width) || (kidYMost > aDesiredSize.height)) {
+        aDesiredSize.mCombinedArea.x = 0;
+        aDesiredSize.mCombinedArea.y = 0;
+        aDesiredSize.mCombinedArea.width = PR_MAX(aDesiredSize.width, kidXMost);
+        aDesiredSize.mCombinedArea.height = PR_MAX(aDesiredSize.height, kidYMost);
+        mState |= NS_FRAME_OUTSIDE_CHILDREN;
+
+      } else {
+        mState &= ~NS_FRAME_OUTSIDE_CHILDREN;
+      }
+
+    } else {
+      mState &= ~NS_FRAME_OUTSIDE_CHILDREN;
+    }
+
     // XXX Temporary hack. Remember this for later when our parent resizes us
     mNaturalHeight = aDesiredSize.height;
   }
diff --git a/mozilla/layout/html/base/src/nsScrollFrame.cpp b/mozilla/layout/html/base/src/nsScrollFrame.cpp
index c4720a5d68e..da1a3bb0385 100644
--- a/mozilla/layout/html/base/src/nsScrollFrame.cpp
+++ b/mozilla/layout/html/base/src/nsScrollFrame.cpp
@@ -333,7 +333,16 @@ nsScrollFrame::Reflow(nsIPresContext&          aPresContext,
               aStatus);
   NS_ASSERTION(NS_FRAME_IS_COMPLETE(aStatus), "bad status");
 
-  // If it's an area frame then get the total size, which includes the
+  // If the frame has child frames that stick outside its bounds, then take
+  // them into account, too
+  nsFrameState  kidState;
+  kidFrame->GetFrameState(kidState);
+  if (NS_FRAME_OUTSIDE_CHILDREN & kidState) {
+    kidDesiredSize.width = kidDesiredSize.mCombinedArea.width;
+    kidDesiredSize.height = kidDesiredSize.mCombinedArea.height;
+  }
+
+  // If it's an area frame, then get the total size which includes the
   // space taken up by absolutely positioned child elements
   nsIAreaFrame* areaFrame;
   if (NS_SUCCEEDED(kidFrame->QueryInterface(kAreaFrameIID, (void**)&areaFrame))) {
@@ -383,7 +392,16 @@ nsScrollFrame::Reflow(nsIPresContext&          aPresContext,
                   aStatus);
       NS_ASSERTION(NS_FRAME_IS_COMPLETE(aStatus), "bad status");
 
-      // If it's an area frame then get the total size, which includes the
+      // If the frame has child frames that stick outside its bounds, then take
+      // them into account, too
+      nsFrameState  kidState;
+      kidFrame->GetFrameState(kidState);
+      if (NS_FRAME_OUTSIDE_CHILDREN & kidState) {
+        kidDesiredSize.width = kidDesiredSize.mCombinedArea.width;
+        kidDesiredSize.height = kidDesiredSize.mCombinedArea.height;
+      }
+
+      // If it's an area frame, then get the total size which includes the
       // space taken up by absolutely positioned child elements
       nsIAreaFrame* areaFrame;
       if (NS_SUCCEEDED(kidFrame->QueryInterface(kAreaFrameIID, (void**)&areaFrame))) {