diff --git a/layout/generic/nsBlockFrame.cpp b/layout/generic/nsBlockFrame.cpp
index 3d04a7c8cad3..b53a64df932a 100644
--- a/layout/generic/nsBlockFrame.cpp
+++ b/layout/generic/nsBlockFrame.cpp
@@ -157,7 +157,8 @@ InitDebugFlags()
 #undef NOISY_REFLOW_REASON        // gives a little info about why each reflow was requested
 #undef REFLOW_STATUS_COVERAGE     // I think this is most useful for printing, to see which frames return "incomplete"
 #undef NOISY_SPACEMANAGER         // enables debug output for space manager use, useful for analysing reflow of floaters and positioned elements
-#undef NOISY_BLOCK_INVALIDATE    // enables debug output for all calls to invalidate
+#undef NOISY_BLOCK_INVALIDATE     // enables debug output for all calls to invalidate
+#undef REALLY_NOISY_REFLOW       // some extra debug info
 
 #endif
 
@@ -781,7 +782,8 @@ nsBlockReflowState::ComputeBlockAvailSpace(nsIFrame* aFrame,
 
   const nsMargin& borderPadding = BorderPadding();
 
-  if (NS_FRAME_SPLITTABLE_NON_RECTANGULAR == aSplitType) {
+  if (NS_FRAME_SPLITTABLE_NON_RECTANGULAR == aSplitType) 
+  {
     if (mBand.GetFloaterCount()) {
       // Use the float-edge property to determine how the child block
       // will interact with the floater.
@@ -2006,15 +2008,6 @@ HaveAutoWidth(const nsHTMLReflowState& aReflowState)
 }
 
 
-static PRBool
-IsPercentageUnitSides(const nsStyleSides* aSides)
-{
-  return eStyleUnit_Percent == aSides->GetLeftUnit()
-      || eStyleUnit_Percent == aSides->GetRightUnit()
-      || eStyleUnit_Percent == aSides->GetTopUnit()
-      || eStyleUnit_Percent == aSides->GetBottomUnit();
-}
-
 static PRBool
 IsPercentageAwareChild(const nsIFrame* aFrame)
 {
@@ -2024,9 +2017,9 @@ IsPercentageAwareChild(const nsIFrame* aFrame)
     return PR_TRUE; // just to be on the safe side
   }
 
-  if (IsPercentageUnitSides(&space->mMargin)
-    || IsPercentageUnitSides(&space->mPadding)
-    || IsPercentageUnitSides(&space->mBorderRadius)) {
+  if (nsLineLayout::IsPercentageUnitSides(&space->mMargin)
+    || nsLineLayout::IsPercentageUnitSides(&space->mPadding)
+    || nsLineLayout::IsPercentageUnitSides(&space->mBorderRadius)) {
     return PR_TRUE;
   }
 
@@ -2042,7 +2035,7 @@ IsPercentageAwareChild(const nsIFrame* aFrame)
     || eStyleUnit_Percent == pos->mHeight.GetUnit()
     || eStyleUnit_Percent == pos->mMinHeight.GetUnit()
     || eStyleUnit_Percent == pos->mMaxHeight.GetUnit()
-    || IsPercentageUnitSides(&pos->mOffset)) { // XXX need more here!!!
+    || nsLineLayout::IsPercentageUnitSides(&pos->mOffset)) { // XXX need more here!!!
     return PR_TRUE;
   }
 
@@ -2600,6 +2593,7 @@ nsBlockFrame::PrepareResizeReflow(nsBlockReflowState& aState)
           // newlines. Therefore, we don't need to reflow the line.
         }
         else if ((line->mNext && !line->HasBreak()) ||
+			           line->ResizeReflowOptimizationDisabled() ||
                  line->HasFloaters() || line->IsImpactedByFloater() ||
                  line->HasPercentageChild() ||
                  (line->mBounds.XMost() > newAvailWidth)) {
diff --git a/layout/generic/nsBlockReflowState.cpp b/layout/generic/nsBlockReflowState.cpp
index 3d04a7c8cad3..b53a64df932a 100644
--- a/layout/generic/nsBlockReflowState.cpp
+++ b/layout/generic/nsBlockReflowState.cpp
@@ -157,7 +157,8 @@ InitDebugFlags()
 #undef NOISY_REFLOW_REASON        // gives a little info about why each reflow was requested
 #undef REFLOW_STATUS_COVERAGE     // I think this is most useful for printing, to see which frames return "incomplete"
 #undef NOISY_SPACEMANAGER         // enables debug output for space manager use, useful for analysing reflow of floaters and positioned elements
-#undef NOISY_BLOCK_INVALIDATE    // enables debug output for all calls to invalidate
+#undef NOISY_BLOCK_INVALIDATE     // enables debug output for all calls to invalidate
+#undef REALLY_NOISY_REFLOW       // some extra debug info
 
 #endif
 
@@ -781,7 +782,8 @@ nsBlockReflowState::ComputeBlockAvailSpace(nsIFrame* aFrame,
 
   const nsMargin& borderPadding = BorderPadding();
 
-  if (NS_FRAME_SPLITTABLE_NON_RECTANGULAR == aSplitType) {
+  if (NS_FRAME_SPLITTABLE_NON_RECTANGULAR == aSplitType) 
+  {
     if (mBand.GetFloaterCount()) {
       // Use the float-edge property to determine how the child block
       // will interact with the floater.
@@ -2006,15 +2008,6 @@ HaveAutoWidth(const nsHTMLReflowState& aReflowState)
 }
 
 
-static PRBool
-IsPercentageUnitSides(const nsStyleSides* aSides)
-{
-  return eStyleUnit_Percent == aSides->GetLeftUnit()
-      || eStyleUnit_Percent == aSides->GetRightUnit()
-      || eStyleUnit_Percent == aSides->GetTopUnit()
-      || eStyleUnit_Percent == aSides->GetBottomUnit();
-}
-
 static PRBool
 IsPercentageAwareChild(const nsIFrame* aFrame)
 {
@@ -2024,9 +2017,9 @@ IsPercentageAwareChild(const nsIFrame* aFrame)
     return PR_TRUE; // just to be on the safe side
   }
 
-  if (IsPercentageUnitSides(&space->mMargin)
-    || IsPercentageUnitSides(&space->mPadding)
-    || IsPercentageUnitSides(&space->mBorderRadius)) {
+  if (nsLineLayout::IsPercentageUnitSides(&space->mMargin)
+    || nsLineLayout::IsPercentageUnitSides(&space->mPadding)
+    || nsLineLayout::IsPercentageUnitSides(&space->mBorderRadius)) {
     return PR_TRUE;
   }
 
@@ -2042,7 +2035,7 @@ IsPercentageAwareChild(const nsIFrame* aFrame)
     || eStyleUnit_Percent == pos->mHeight.GetUnit()
     || eStyleUnit_Percent == pos->mMinHeight.GetUnit()
     || eStyleUnit_Percent == pos->mMaxHeight.GetUnit()
-    || IsPercentageUnitSides(&pos->mOffset)) { // XXX need more here!!!
+    || nsLineLayout::IsPercentageUnitSides(&pos->mOffset)) { // XXX need more here!!!
     return PR_TRUE;
   }
 
@@ -2600,6 +2593,7 @@ nsBlockFrame::PrepareResizeReflow(nsBlockReflowState& aState)
           // newlines. Therefore, we don't need to reflow the line.
         }
         else if ((line->mNext && !line->HasBreak()) ||
+			           line->ResizeReflowOptimizationDisabled() ||
                  line->HasFloaters() || line->IsImpactedByFloater() ||
                  line->HasPercentageChild() ||
                  (line->mBounds.XMost() > newAvailWidth)) {
diff --git a/layout/generic/nsBlockReflowState.h b/layout/generic/nsBlockReflowState.h
index 3d04a7c8cad3..b53a64df932a 100644
--- a/layout/generic/nsBlockReflowState.h
+++ b/layout/generic/nsBlockReflowState.h
@@ -157,7 +157,8 @@ InitDebugFlags()
 #undef NOISY_REFLOW_REASON        // gives a little info about why each reflow was requested
 #undef REFLOW_STATUS_COVERAGE     // I think this is most useful for printing, to see which frames return "incomplete"
 #undef NOISY_SPACEMANAGER         // enables debug output for space manager use, useful for analysing reflow of floaters and positioned elements
-#undef NOISY_BLOCK_INVALIDATE    // enables debug output for all calls to invalidate
+#undef NOISY_BLOCK_INVALIDATE     // enables debug output for all calls to invalidate
+#undef REALLY_NOISY_REFLOW       // some extra debug info
 
 #endif
 
@@ -781,7 +782,8 @@ nsBlockReflowState::ComputeBlockAvailSpace(nsIFrame* aFrame,
 
   const nsMargin& borderPadding = BorderPadding();
 
-  if (NS_FRAME_SPLITTABLE_NON_RECTANGULAR == aSplitType) {
+  if (NS_FRAME_SPLITTABLE_NON_RECTANGULAR == aSplitType) 
+  {
     if (mBand.GetFloaterCount()) {
       // Use the float-edge property to determine how the child block
       // will interact with the floater.
@@ -2006,15 +2008,6 @@ HaveAutoWidth(const nsHTMLReflowState& aReflowState)
 }
 
 
-static PRBool
-IsPercentageUnitSides(const nsStyleSides* aSides)
-{
-  return eStyleUnit_Percent == aSides->GetLeftUnit()
-      || eStyleUnit_Percent == aSides->GetRightUnit()
-      || eStyleUnit_Percent == aSides->GetTopUnit()
-      || eStyleUnit_Percent == aSides->GetBottomUnit();
-}
-
 static PRBool
 IsPercentageAwareChild(const nsIFrame* aFrame)
 {
@@ -2024,9 +2017,9 @@ IsPercentageAwareChild(const nsIFrame* aFrame)
     return PR_TRUE; // just to be on the safe side
   }
 
-  if (IsPercentageUnitSides(&space->mMargin)
-    || IsPercentageUnitSides(&space->mPadding)
-    || IsPercentageUnitSides(&space->mBorderRadius)) {
+  if (nsLineLayout::IsPercentageUnitSides(&space->mMargin)
+    || nsLineLayout::IsPercentageUnitSides(&space->mPadding)
+    || nsLineLayout::IsPercentageUnitSides(&space->mBorderRadius)) {
     return PR_TRUE;
   }
 
@@ -2042,7 +2035,7 @@ IsPercentageAwareChild(const nsIFrame* aFrame)
     || eStyleUnit_Percent == pos->mHeight.GetUnit()
     || eStyleUnit_Percent == pos->mMinHeight.GetUnit()
     || eStyleUnit_Percent == pos->mMaxHeight.GetUnit()
-    || IsPercentageUnitSides(&pos->mOffset)) { // XXX need more here!!!
+    || nsLineLayout::IsPercentageUnitSides(&pos->mOffset)) { // XXX need more here!!!
     return PR_TRUE;
   }
 
@@ -2600,6 +2593,7 @@ nsBlockFrame::PrepareResizeReflow(nsBlockReflowState& aState)
           // newlines. Therefore, we don't need to reflow the line.
         }
         else if ((line->mNext && !line->HasBreak()) ||
+			           line->ResizeReflowOptimizationDisabled() ||
                  line->HasFloaters() || line->IsImpactedByFloater() ||
                  line->HasPercentageChild() ||
                  (line->mBounds.XMost() > newAvailWidth)) {
diff --git a/layout/generic/nsInlineFrame.cpp b/layout/generic/nsInlineFrame.cpp
index e0e1fe972111..4b624ed1cc30 100644
--- a/layout/generic/nsInlineFrame.cpp
+++ b/layout/generic/nsInlineFrame.cpp
@@ -549,6 +549,41 @@ nsInlineFrame::ReflowFrames(nsIPresContext* aPresContext,
   return rv;
 }
 
+static 
+void SetContainsPercentAwareChild(nsIFrame *aFrame)
+{
+  nsFrameState myFrameState;
+  aFrame->GetFrameState(&myFrameState);
+  aFrame->SetFrameState(myFrameState | NS_INLINE_FRAME_CONTAINS_PERCENT_AWARE_CHILD);
+}
+
+static
+void MarkPercentAwareFrame(nsIPresContext *aPresContext, 
+                           nsInlineFrame  *aInline,
+                           nsIFrame       *aFrame)
+{
+  nsFrameState childFrameState;
+  aFrame->GetFrameState(&childFrameState);
+  if (childFrameState & NS_FRAME_REPLACED_ELEMENT) 
+  { // aFrame is a replaced element, check it's style
+    if (nsLineLayout::IsPercentageAwareReplacedElement(aPresContext, aFrame)) {
+      SetContainsPercentAwareChild(aInline);
+    }
+  }
+  else
+  {
+    nsIFrame *child;
+    aFrame->FirstChild(aPresContext, nsnull, &child);
+    if (child)
+    { // aFrame is an inline container frame, check my frame state
+      if (childFrameState & NS_INLINE_FRAME_CONTAINS_PERCENT_AWARE_CHILD) {
+        SetContainsPercentAwareChild(aInline); // if a child container is effected, so am I
+      }
+    }
+    // else frame is a leaf that we don't care about
+  }   
+}
+
 nsresult
 nsInlineFrame::ReflowInlineFrame(nsIPresContext* aPresContext,
                                  const nsHTMLReflowState& aReflowState,
@@ -561,6 +596,15 @@ nsInlineFrame::ReflowInlineFrame(nsIPresContext* aPresContext,
   PRBool pushedFrame;
   nsresult rv = lineLayout->ReflowFrame(aFrame, &irs.mNextRCFrame, aStatus,
                                         nsnull, pushedFrame);
+  /* This next block is for bug 28811
+     Test the child frame for %-awareness, 
+     and mark this frame with a bit if it is %-aware.
+     Don't bother if this frame is already marked
+  */
+  if (!(mState & NS_INLINE_FRAME_CONTAINS_PERCENT_AWARE_CHILD)) {  
+    MarkPercentAwareFrame(aPresContext, this, aFrame);
+  }
+
   if (NS_FAILED(rv)) {
     return rv;
   }
diff --git a/layout/generic/nsInlineFrame.h b/layout/generic/nsInlineFrame.h
index 93a9245d68e0..29c6e6e69bc1 100644
--- a/layout/generic/nsInlineFrame.h
+++ b/layout/generic/nsInlineFrame.h
@@ -33,6 +33,8 @@ class nsAnonymousBlockFrame;
 
 #define nsInlineFrameSuper nsHTMLContainerFrame
 
+#define NS_INLINE_FRAME_CONTAINS_PERCENT_AWARE_CHILD 0X00010000
+
 /**
  * Inline frame class.
  *
@@ -95,8 +97,8 @@ protected:
     nsIFrame* mNextRCFrame;
     nsIFrame* mPrevFrame;
     nsInlineFrame* mNextInFlow;
-    PRBool mSetParentPointer;  // when reflowing child frame first set its
-                               // parent frame pointer
+    PRPackedBool mSetParentPointer;  // when reflowing child frame first set its
+                                     // parent frame pointer
 
     InlineReflowState()  {
       mNextRCFrame = nsnull;
@@ -129,6 +131,7 @@ protected:
   virtual void PushFrames(nsIPresContext* aPresContext,
                           nsIFrame* aFromChild,
                           nsIFrame* aPrevSibling);
+
 };
 
 //----------------------------------------------------------------------
diff --git a/layout/generic/nsLineBox.h b/layout/generic/nsLineBox.h
index a89a45661083..e809724f6e83 100644
--- a/layout/generic/nsLineBox.h
+++ b/layout/generic/nsLineBox.h
@@ -136,7 +136,7 @@ protected:
 //----------------------------------------------------------------------
 
 #define LINE_MAX_BREAK_TYPE  ((1 << 4) - 1)
-#define LINE_MAX_CHILD_COUNT ((1 << 21) - 1)
+#define LINE_MAX_CHILD_COUNT ((1 << 20) - 1)
 
 #if NS_STYLE_CLEAR_LAST_VALUE > 15
 need to rearrange the mBits bitfield;
@@ -231,6 +231,17 @@ public:
   PRBool IsForceInvalidate() const {
     return mFlags.mForceInvalidate;
   }
+
+  // mResizeReflowOptimizationDisabled bit
+  void DisableResizeReflowOptimization() {
+    mFlags.mResizeReflowOptimizationDisabled = PR_TRUE;
+  }
+  void EnableResizeReflowOptimization() {
+    mFlags.mResizeReflowOptimizationDisabled = PR_FALSE;
+  }
+  PRBool ResizeReflowOptimizationDisabled() const {
+    return mFlags.mResizeReflowOptimizationDisabled;
+  }
   
   // mChildCount value
   PRInt32 GetChildCount() const {
@@ -337,11 +348,11 @@ public:
     PRUint32 mTrimmed : 1;
     PRUint32 mHasPercentageChild : 1;
     PRUint32 mLineWrapped: 1;
-    PRUint32 mForceInvalidate: 1;
-
+    PRUint32 mForceInvalidate: 1;                   // default 0 = means this line handles it's own invalidation.  1 = always invalidate this entire line
+	  PRUint32 mResizeReflowOptimizationDisabled: 1;  // default 0 = means that the opt potentially applies to this line. 1 = never skip reflowing this line for a resize reflow
     PRUint32 mBreakType : 4;
 
-    PRUint32 mChildCount : 21;
+    PRUint32 mChildCount : 20;
   };
 
   struct ExtraData {
@@ -442,7 +453,7 @@ protected:
   nsLineBox** mLines;
   PRInt32 mIndex;
   PRInt32 mNumLines;
-  PRBool mRightToLeft;
+  PRPackedBool mRightToLeft;
 };
 
 #endif /* nsLineBox_h___ */
diff --git a/layout/generic/nsLineLayout.cpp b/layout/generic/nsLineLayout.cpp
index 02e9740eba9a..e55f87e4015e 100644
--- a/layout/generic/nsLineLayout.cpp
+++ b/layout/generic/nsLineLayout.cpp
@@ -26,6 +26,7 @@
 #include "nsCOMPtr.h"
 #include "nsLineLayout.h"
 #include "nsBlockFrame.h"
+#include "nsInlineFrame.h"
 #include "nsStyleConsts.h"
 #include "nsHTMLContainerFrame.h"
 #include "nsHTMLIIDs.h"
@@ -1548,6 +1549,86 @@ nsLineLayout::DumpPerSpanData(PerSpanData* psd, PRInt32 aIndent)
 #define VALIGN_TOP    1
 #define VALIGN_BOTTOM 2
 
+PRBool
+nsLineLayout::IsPercentageUnitSides(const nsStyleSides* aSides)
+{
+  return eStyleUnit_Percent == aSides->GetLeftUnit()
+      || eStyleUnit_Percent == aSides->GetRightUnit()
+      || eStyleUnit_Percent == aSides->GetTopUnit()
+      || eStyleUnit_Percent == aSides->GetBottomUnit();
+}
+
+PRBool
+nsLineLayout::IsPercentageAwareReplacedElement(nsIPresContext *aPresContext, 
+                                               nsIFrame* aFrame)
+{
+  nsFrameState frameState;
+  aFrame->GetFrameState(&frameState);
+  if (frameState & NS_FRAME_REPLACED_ELEMENT)
+  {
+    nsCOMPtr<nsIAtom> frameType;
+    aFrame->GetFrameType(getter_AddRefs(frameType));
+    if (nsLayoutAtoms::brFrame != frameType && 
+        nsLayoutAtoms::textFrame != frameType)
+    {
+      const nsStyleSpacing* space;
+      nsresult rv = aFrame->GetStyleData(eStyleStruct_Spacing,(const nsStyleStruct*&) space);
+      if (NS_FAILED(rv)) {
+        return PR_TRUE; // just to be on the safe side
+      }
+
+      if (IsPercentageUnitSides(&space->mMargin)
+        || IsPercentageUnitSides(&space->mPadding)
+        || IsPercentageUnitSides(&space->mBorderRadius)) {
+        return PR_TRUE;
+      }
+
+      const nsStylePosition* pos;
+      rv = aFrame->GetStyleData(eStyleStruct_Position,(const nsStyleStruct*&) pos);
+      if (NS_FAILED(rv)) {
+        return PR_TRUE; // just to be on the safe side
+      }
+
+      if (eStyleUnit_Percent == pos->mWidth.GetUnit()
+        || eStyleUnit_Percent == pos->mMaxWidth.GetUnit()
+        || eStyleUnit_Percent == pos->mMinWidth.GetUnit()
+        || eStyleUnit_Percent == pos->mHeight.GetUnit()
+        || eStyleUnit_Percent == pos->mMinHeight.GetUnit()
+        || eStyleUnit_Percent == pos->mMaxHeight.GetUnit()
+        || IsPercentageUnitSides(&pos->mOffset)) { // XXX need more here!!!
+        return PR_TRUE;
+      }
+    }
+  }
+
+  return PR_FALSE;
+}
+
+PRBool IsPercentageAwareFrame(nsIPresContext *aPresContext, nsIFrame *aFrame)
+{
+  nsFrameState childFrameState;
+  aFrame->GetFrameState(&childFrameState);
+  if (childFrameState & NS_FRAME_REPLACED_ELEMENT) {
+    if (nsLineLayout::IsPercentageAwareReplacedElement(aPresContext, aFrame)) {
+      return PR_TRUE;
+    }
+  }
+  else
+  {
+    nsIFrame *child;
+    aFrame->FirstChild(aPresContext, nsnull, &child);
+    if (child)
+    { // aFrame is an inline container frame, check my frame state
+      if (childFrameState & NS_INLINE_FRAME_CONTAINS_PERCENT_AWARE_CHILD) {
+        return PR_TRUE;
+      }
+    }
+    // else it's a frame we just don't care about
+  }  
+  return PR_FALSE;
+}
+
+
 void
 nsLineLayout::VerticalAlignFrames(nsLineBox* aLineBox,
                                   nsSize& aMaxElementSizeResult,
@@ -1684,6 +1765,14 @@ nsLineLayout::VerticalAlignFrames(nsLineBox* aLineBox,
       nscoord distanceFromTop = pfd->mBounds.y - mTopEdge;
       PlaceTopBottomFrames(span, distanceFromTop, lineHeight);
     }
+    // check to see if the frame is an inline replace element
+    // and if it is percent-aware.  If so, mark the line.
+    if ((PR_FALSE==aLineBox->ResizeReflowOptimizationDisabled()) &&
+         pfd->mFrameType & NS_CSS_FRAME_TYPE_INLINE)
+    {
+      if (IsPercentageAwareFrame(mPresContext, pfd->mFrame))
+        aLineBox->DisableResizeReflowOptimization();
+    }
     pfd = pfd->mNext;
   }
 
diff --git a/layout/generic/nsLineLayout.h b/layout/generic/nsLineLayout.h
index 38914d0bdd28..d62ee935b315 100644
--- a/layout/generic/nsLineLayout.h
+++ b/layout/generic/nsLineLayout.h
@@ -251,6 +251,12 @@ public:
 
   static PRBool TreatFrameAsBlock(nsIFrame* aFrame);
 
+  static PRBool IsPercentageUnitSides(const nsStyleSides* aSides);
+
+  static PRBool IsPercentageAwareReplacedElement(nsIPresContext *aPresContext, 
+                                                 nsIFrame       *aFrame);
+
+
   //----------------------------------------
 
   nsIPresContext* mPresContext;
diff --git a/layout/html/base/src/nsBlockFrame.cpp b/layout/html/base/src/nsBlockFrame.cpp
index 3d04a7c8cad3..b53a64df932a 100644
--- a/layout/html/base/src/nsBlockFrame.cpp
+++ b/layout/html/base/src/nsBlockFrame.cpp
@@ -157,7 +157,8 @@ InitDebugFlags()
 #undef NOISY_REFLOW_REASON        // gives a little info about why each reflow was requested
 #undef REFLOW_STATUS_COVERAGE     // I think this is most useful for printing, to see which frames return "incomplete"
 #undef NOISY_SPACEMANAGER         // enables debug output for space manager use, useful for analysing reflow of floaters and positioned elements
-#undef NOISY_BLOCK_INVALIDATE    // enables debug output for all calls to invalidate
+#undef NOISY_BLOCK_INVALIDATE     // enables debug output for all calls to invalidate
+#undef REALLY_NOISY_REFLOW       // some extra debug info
 
 #endif
 
@@ -781,7 +782,8 @@ nsBlockReflowState::ComputeBlockAvailSpace(nsIFrame* aFrame,
 
   const nsMargin& borderPadding = BorderPadding();
 
-  if (NS_FRAME_SPLITTABLE_NON_RECTANGULAR == aSplitType) {
+  if (NS_FRAME_SPLITTABLE_NON_RECTANGULAR == aSplitType) 
+  {
     if (mBand.GetFloaterCount()) {
       // Use the float-edge property to determine how the child block
       // will interact with the floater.
@@ -2006,15 +2008,6 @@ HaveAutoWidth(const nsHTMLReflowState& aReflowState)
 }
 
 
-static PRBool
-IsPercentageUnitSides(const nsStyleSides* aSides)
-{
-  return eStyleUnit_Percent == aSides->GetLeftUnit()
-      || eStyleUnit_Percent == aSides->GetRightUnit()
-      || eStyleUnit_Percent == aSides->GetTopUnit()
-      || eStyleUnit_Percent == aSides->GetBottomUnit();
-}
-
 static PRBool
 IsPercentageAwareChild(const nsIFrame* aFrame)
 {
@@ -2024,9 +2017,9 @@ IsPercentageAwareChild(const nsIFrame* aFrame)
     return PR_TRUE; // just to be on the safe side
   }
 
-  if (IsPercentageUnitSides(&space->mMargin)
-    || IsPercentageUnitSides(&space->mPadding)
-    || IsPercentageUnitSides(&space->mBorderRadius)) {
+  if (nsLineLayout::IsPercentageUnitSides(&space->mMargin)
+    || nsLineLayout::IsPercentageUnitSides(&space->mPadding)
+    || nsLineLayout::IsPercentageUnitSides(&space->mBorderRadius)) {
     return PR_TRUE;
   }
 
@@ -2042,7 +2035,7 @@ IsPercentageAwareChild(const nsIFrame* aFrame)
     || eStyleUnit_Percent == pos->mHeight.GetUnit()
     || eStyleUnit_Percent == pos->mMinHeight.GetUnit()
     || eStyleUnit_Percent == pos->mMaxHeight.GetUnit()
-    || IsPercentageUnitSides(&pos->mOffset)) { // XXX need more here!!!
+    || nsLineLayout::IsPercentageUnitSides(&pos->mOffset)) { // XXX need more here!!!
     return PR_TRUE;
   }
 
@@ -2600,6 +2593,7 @@ nsBlockFrame::PrepareResizeReflow(nsBlockReflowState& aState)
           // newlines. Therefore, we don't need to reflow the line.
         }
         else if ((line->mNext && !line->HasBreak()) ||
+			           line->ResizeReflowOptimizationDisabled() ||
                  line->HasFloaters() || line->IsImpactedByFloater() ||
                  line->HasPercentageChild() ||
                  (line->mBounds.XMost() > newAvailWidth)) {
diff --git a/layout/html/base/src/nsBlockReflowState.cpp b/layout/html/base/src/nsBlockReflowState.cpp
index 3d04a7c8cad3..b53a64df932a 100644
--- a/layout/html/base/src/nsBlockReflowState.cpp
+++ b/layout/html/base/src/nsBlockReflowState.cpp
@@ -157,7 +157,8 @@ InitDebugFlags()
 #undef NOISY_REFLOW_REASON        // gives a little info about why each reflow was requested
 #undef REFLOW_STATUS_COVERAGE     // I think this is most useful for printing, to see which frames return "incomplete"
 #undef NOISY_SPACEMANAGER         // enables debug output for space manager use, useful for analysing reflow of floaters and positioned elements
-#undef NOISY_BLOCK_INVALIDATE    // enables debug output for all calls to invalidate
+#undef NOISY_BLOCK_INVALIDATE     // enables debug output for all calls to invalidate
+#undef REALLY_NOISY_REFLOW       // some extra debug info
 
 #endif
 
@@ -781,7 +782,8 @@ nsBlockReflowState::ComputeBlockAvailSpace(nsIFrame* aFrame,
 
   const nsMargin& borderPadding = BorderPadding();
 
-  if (NS_FRAME_SPLITTABLE_NON_RECTANGULAR == aSplitType) {
+  if (NS_FRAME_SPLITTABLE_NON_RECTANGULAR == aSplitType) 
+  {
     if (mBand.GetFloaterCount()) {
       // Use the float-edge property to determine how the child block
       // will interact with the floater.
@@ -2006,15 +2008,6 @@ HaveAutoWidth(const nsHTMLReflowState& aReflowState)
 }
 
 
-static PRBool
-IsPercentageUnitSides(const nsStyleSides* aSides)
-{
-  return eStyleUnit_Percent == aSides->GetLeftUnit()
-      || eStyleUnit_Percent == aSides->GetRightUnit()
-      || eStyleUnit_Percent == aSides->GetTopUnit()
-      || eStyleUnit_Percent == aSides->GetBottomUnit();
-}
-
 static PRBool
 IsPercentageAwareChild(const nsIFrame* aFrame)
 {
@@ -2024,9 +2017,9 @@ IsPercentageAwareChild(const nsIFrame* aFrame)
     return PR_TRUE; // just to be on the safe side
   }
 
-  if (IsPercentageUnitSides(&space->mMargin)
-    || IsPercentageUnitSides(&space->mPadding)
-    || IsPercentageUnitSides(&space->mBorderRadius)) {
+  if (nsLineLayout::IsPercentageUnitSides(&space->mMargin)
+    || nsLineLayout::IsPercentageUnitSides(&space->mPadding)
+    || nsLineLayout::IsPercentageUnitSides(&space->mBorderRadius)) {
     return PR_TRUE;
   }
 
@@ -2042,7 +2035,7 @@ IsPercentageAwareChild(const nsIFrame* aFrame)
     || eStyleUnit_Percent == pos->mHeight.GetUnit()
     || eStyleUnit_Percent == pos->mMinHeight.GetUnit()
     || eStyleUnit_Percent == pos->mMaxHeight.GetUnit()
-    || IsPercentageUnitSides(&pos->mOffset)) { // XXX need more here!!!
+    || nsLineLayout::IsPercentageUnitSides(&pos->mOffset)) { // XXX need more here!!!
     return PR_TRUE;
   }
 
@@ -2600,6 +2593,7 @@ nsBlockFrame::PrepareResizeReflow(nsBlockReflowState& aState)
           // newlines. Therefore, we don't need to reflow the line.
         }
         else if ((line->mNext && !line->HasBreak()) ||
+			           line->ResizeReflowOptimizationDisabled() ||
                  line->HasFloaters() || line->IsImpactedByFloater() ||
                  line->HasPercentageChild() ||
                  (line->mBounds.XMost() > newAvailWidth)) {
diff --git a/layout/html/base/src/nsBlockReflowState.h b/layout/html/base/src/nsBlockReflowState.h
index 3d04a7c8cad3..b53a64df932a 100644
--- a/layout/html/base/src/nsBlockReflowState.h
+++ b/layout/html/base/src/nsBlockReflowState.h
@@ -157,7 +157,8 @@ InitDebugFlags()
 #undef NOISY_REFLOW_REASON        // gives a little info about why each reflow was requested
 #undef REFLOW_STATUS_COVERAGE     // I think this is most useful for printing, to see which frames return "incomplete"
 #undef NOISY_SPACEMANAGER         // enables debug output for space manager use, useful for analysing reflow of floaters and positioned elements
-#undef NOISY_BLOCK_INVALIDATE    // enables debug output for all calls to invalidate
+#undef NOISY_BLOCK_INVALIDATE     // enables debug output for all calls to invalidate
+#undef REALLY_NOISY_REFLOW       // some extra debug info
 
 #endif
 
@@ -781,7 +782,8 @@ nsBlockReflowState::ComputeBlockAvailSpace(nsIFrame* aFrame,
 
   const nsMargin& borderPadding = BorderPadding();
 
-  if (NS_FRAME_SPLITTABLE_NON_RECTANGULAR == aSplitType) {
+  if (NS_FRAME_SPLITTABLE_NON_RECTANGULAR == aSplitType) 
+  {
     if (mBand.GetFloaterCount()) {
       // Use the float-edge property to determine how the child block
       // will interact with the floater.
@@ -2006,15 +2008,6 @@ HaveAutoWidth(const nsHTMLReflowState& aReflowState)
 }
 
 
-static PRBool
-IsPercentageUnitSides(const nsStyleSides* aSides)
-{
-  return eStyleUnit_Percent == aSides->GetLeftUnit()
-      || eStyleUnit_Percent == aSides->GetRightUnit()
-      || eStyleUnit_Percent == aSides->GetTopUnit()
-      || eStyleUnit_Percent == aSides->GetBottomUnit();
-}
-
 static PRBool
 IsPercentageAwareChild(const nsIFrame* aFrame)
 {
@@ -2024,9 +2017,9 @@ IsPercentageAwareChild(const nsIFrame* aFrame)
     return PR_TRUE; // just to be on the safe side
   }
 
-  if (IsPercentageUnitSides(&space->mMargin)
-    || IsPercentageUnitSides(&space->mPadding)
-    || IsPercentageUnitSides(&space->mBorderRadius)) {
+  if (nsLineLayout::IsPercentageUnitSides(&space->mMargin)
+    || nsLineLayout::IsPercentageUnitSides(&space->mPadding)
+    || nsLineLayout::IsPercentageUnitSides(&space->mBorderRadius)) {
     return PR_TRUE;
   }
 
@@ -2042,7 +2035,7 @@ IsPercentageAwareChild(const nsIFrame* aFrame)
     || eStyleUnit_Percent == pos->mHeight.GetUnit()
     || eStyleUnit_Percent == pos->mMinHeight.GetUnit()
     || eStyleUnit_Percent == pos->mMaxHeight.GetUnit()
-    || IsPercentageUnitSides(&pos->mOffset)) { // XXX need more here!!!
+    || nsLineLayout::IsPercentageUnitSides(&pos->mOffset)) { // XXX need more here!!!
     return PR_TRUE;
   }
 
@@ -2600,6 +2593,7 @@ nsBlockFrame::PrepareResizeReflow(nsBlockReflowState& aState)
           // newlines. Therefore, we don't need to reflow the line.
         }
         else if ((line->mNext && !line->HasBreak()) ||
+			           line->ResizeReflowOptimizationDisabled() ||
                  line->HasFloaters() || line->IsImpactedByFloater() ||
                  line->HasPercentageChild() ||
                  (line->mBounds.XMost() > newAvailWidth)) {
diff --git a/layout/html/base/src/nsInlineFrame.cpp b/layout/html/base/src/nsInlineFrame.cpp
index e0e1fe972111..4b624ed1cc30 100644
--- a/layout/html/base/src/nsInlineFrame.cpp
+++ b/layout/html/base/src/nsInlineFrame.cpp
@@ -549,6 +549,41 @@ nsInlineFrame::ReflowFrames(nsIPresContext* aPresContext,
   return rv;
 }
 
+static 
+void SetContainsPercentAwareChild(nsIFrame *aFrame)
+{
+  nsFrameState myFrameState;
+  aFrame->GetFrameState(&myFrameState);
+  aFrame->SetFrameState(myFrameState | NS_INLINE_FRAME_CONTAINS_PERCENT_AWARE_CHILD);
+}
+
+static
+void MarkPercentAwareFrame(nsIPresContext *aPresContext, 
+                           nsInlineFrame  *aInline,
+                           nsIFrame       *aFrame)
+{
+  nsFrameState childFrameState;
+  aFrame->GetFrameState(&childFrameState);
+  if (childFrameState & NS_FRAME_REPLACED_ELEMENT) 
+  { // aFrame is a replaced element, check it's style
+    if (nsLineLayout::IsPercentageAwareReplacedElement(aPresContext, aFrame)) {
+      SetContainsPercentAwareChild(aInline);
+    }
+  }
+  else
+  {
+    nsIFrame *child;
+    aFrame->FirstChild(aPresContext, nsnull, &child);
+    if (child)
+    { // aFrame is an inline container frame, check my frame state
+      if (childFrameState & NS_INLINE_FRAME_CONTAINS_PERCENT_AWARE_CHILD) {
+        SetContainsPercentAwareChild(aInline); // if a child container is effected, so am I
+      }
+    }
+    // else frame is a leaf that we don't care about
+  }   
+}
+
 nsresult
 nsInlineFrame::ReflowInlineFrame(nsIPresContext* aPresContext,
                                  const nsHTMLReflowState& aReflowState,
@@ -561,6 +596,15 @@ nsInlineFrame::ReflowInlineFrame(nsIPresContext* aPresContext,
   PRBool pushedFrame;
   nsresult rv = lineLayout->ReflowFrame(aFrame, &irs.mNextRCFrame, aStatus,
                                         nsnull, pushedFrame);
+  /* This next block is for bug 28811
+     Test the child frame for %-awareness, 
+     and mark this frame with a bit if it is %-aware.
+     Don't bother if this frame is already marked
+  */
+  if (!(mState & NS_INLINE_FRAME_CONTAINS_PERCENT_AWARE_CHILD)) {  
+    MarkPercentAwareFrame(aPresContext, this, aFrame);
+  }
+
   if (NS_FAILED(rv)) {
     return rv;
   }
diff --git a/layout/html/base/src/nsInlineFrame.h b/layout/html/base/src/nsInlineFrame.h
index 93a9245d68e0..29c6e6e69bc1 100644
--- a/layout/html/base/src/nsInlineFrame.h
+++ b/layout/html/base/src/nsInlineFrame.h
@@ -33,6 +33,8 @@ class nsAnonymousBlockFrame;
 
 #define nsInlineFrameSuper nsHTMLContainerFrame
 
+#define NS_INLINE_FRAME_CONTAINS_PERCENT_AWARE_CHILD 0X00010000
+
 /**
  * Inline frame class.
  *
@@ -95,8 +97,8 @@ protected:
     nsIFrame* mNextRCFrame;
     nsIFrame* mPrevFrame;
     nsInlineFrame* mNextInFlow;
-    PRBool mSetParentPointer;  // when reflowing child frame first set its
-                               // parent frame pointer
+    PRPackedBool mSetParentPointer;  // when reflowing child frame first set its
+                                     // parent frame pointer
 
     InlineReflowState()  {
       mNextRCFrame = nsnull;
@@ -129,6 +131,7 @@ protected:
   virtual void PushFrames(nsIPresContext* aPresContext,
                           nsIFrame* aFromChild,
                           nsIFrame* aPrevSibling);
+
 };
 
 //----------------------------------------------------------------------
diff --git a/layout/html/base/src/nsLineBox.h b/layout/html/base/src/nsLineBox.h
index a89a45661083..e809724f6e83 100644
--- a/layout/html/base/src/nsLineBox.h
+++ b/layout/html/base/src/nsLineBox.h
@@ -136,7 +136,7 @@ protected:
 //----------------------------------------------------------------------
 
 #define LINE_MAX_BREAK_TYPE  ((1 << 4) - 1)
-#define LINE_MAX_CHILD_COUNT ((1 << 21) - 1)
+#define LINE_MAX_CHILD_COUNT ((1 << 20) - 1)
 
 #if NS_STYLE_CLEAR_LAST_VALUE > 15
 need to rearrange the mBits bitfield;
@@ -231,6 +231,17 @@ public:
   PRBool IsForceInvalidate() const {
     return mFlags.mForceInvalidate;
   }
+
+  // mResizeReflowOptimizationDisabled bit
+  void DisableResizeReflowOptimization() {
+    mFlags.mResizeReflowOptimizationDisabled = PR_TRUE;
+  }
+  void EnableResizeReflowOptimization() {
+    mFlags.mResizeReflowOptimizationDisabled = PR_FALSE;
+  }
+  PRBool ResizeReflowOptimizationDisabled() const {
+    return mFlags.mResizeReflowOptimizationDisabled;
+  }
   
   // mChildCount value
   PRInt32 GetChildCount() const {
@@ -337,11 +348,11 @@ public:
     PRUint32 mTrimmed : 1;
     PRUint32 mHasPercentageChild : 1;
     PRUint32 mLineWrapped: 1;
-    PRUint32 mForceInvalidate: 1;
-
+    PRUint32 mForceInvalidate: 1;                   // default 0 = means this line handles it's own invalidation.  1 = always invalidate this entire line
+	  PRUint32 mResizeReflowOptimizationDisabled: 1;  // default 0 = means that the opt potentially applies to this line. 1 = never skip reflowing this line for a resize reflow
     PRUint32 mBreakType : 4;
 
-    PRUint32 mChildCount : 21;
+    PRUint32 mChildCount : 20;
   };
 
   struct ExtraData {
@@ -442,7 +453,7 @@ protected:
   nsLineBox** mLines;
   PRInt32 mIndex;
   PRInt32 mNumLines;
-  PRBool mRightToLeft;
+  PRPackedBool mRightToLeft;
 };
 
 #endif /* nsLineBox_h___ */
diff --git a/layout/html/base/src/nsLineLayout.cpp b/layout/html/base/src/nsLineLayout.cpp
index 02e9740eba9a..e55f87e4015e 100644
--- a/layout/html/base/src/nsLineLayout.cpp
+++ b/layout/html/base/src/nsLineLayout.cpp
@@ -26,6 +26,7 @@
 #include "nsCOMPtr.h"
 #include "nsLineLayout.h"
 #include "nsBlockFrame.h"
+#include "nsInlineFrame.h"
 #include "nsStyleConsts.h"
 #include "nsHTMLContainerFrame.h"
 #include "nsHTMLIIDs.h"
@@ -1548,6 +1549,86 @@ nsLineLayout::DumpPerSpanData(PerSpanData* psd, PRInt32 aIndent)
 #define VALIGN_TOP    1
 #define VALIGN_BOTTOM 2
 
+PRBool
+nsLineLayout::IsPercentageUnitSides(const nsStyleSides* aSides)
+{
+  return eStyleUnit_Percent == aSides->GetLeftUnit()
+      || eStyleUnit_Percent == aSides->GetRightUnit()
+      || eStyleUnit_Percent == aSides->GetTopUnit()
+      || eStyleUnit_Percent == aSides->GetBottomUnit();
+}
+
+PRBool
+nsLineLayout::IsPercentageAwareReplacedElement(nsIPresContext *aPresContext, 
+                                               nsIFrame* aFrame)
+{
+  nsFrameState frameState;
+  aFrame->GetFrameState(&frameState);
+  if (frameState & NS_FRAME_REPLACED_ELEMENT)
+  {
+    nsCOMPtr<nsIAtom> frameType;
+    aFrame->GetFrameType(getter_AddRefs(frameType));
+    if (nsLayoutAtoms::brFrame != frameType && 
+        nsLayoutAtoms::textFrame != frameType)
+    {
+      const nsStyleSpacing* space;
+      nsresult rv = aFrame->GetStyleData(eStyleStruct_Spacing,(const nsStyleStruct*&) space);
+      if (NS_FAILED(rv)) {
+        return PR_TRUE; // just to be on the safe side
+      }
+
+      if (IsPercentageUnitSides(&space->mMargin)
+        || IsPercentageUnitSides(&space->mPadding)
+        || IsPercentageUnitSides(&space->mBorderRadius)) {
+        return PR_TRUE;
+      }
+
+      const nsStylePosition* pos;
+      rv = aFrame->GetStyleData(eStyleStruct_Position,(const nsStyleStruct*&) pos);
+      if (NS_FAILED(rv)) {
+        return PR_TRUE; // just to be on the safe side
+      }
+
+      if (eStyleUnit_Percent == pos->mWidth.GetUnit()
+        || eStyleUnit_Percent == pos->mMaxWidth.GetUnit()
+        || eStyleUnit_Percent == pos->mMinWidth.GetUnit()
+        || eStyleUnit_Percent == pos->mHeight.GetUnit()
+        || eStyleUnit_Percent == pos->mMinHeight.GetUnit()
+        || eStyleUnit_Percent == pos->mMaxHeight.GetUnit()
+        || IsPercentageUnitSides(&pos->mOffset)) { // XXX need more here!!!
+        return PR_TRUE;
+      }
+    }
+  }
+
+  return PR_FALSE;
+}
+
+PRBool IsPercentageAwareFrame(nsIPresContext *aPresContext, nsIFrame *aFrame)
+{
+  nsFrameState childFrameState;
+  aFrame->GetFrameState(&childFrameState);
+  if (childFrameState & NS_FRAME_REPLACED_ELEMENT) {
+    if (nsLineLayout::IsPercentageAwareReplacedElement(aPresContext, aFrame)) {
+      return PR_TRUE;
+    }
+  }
+  else
+  {
+    nsIFrame *child;
+    aFrame->FirstChild(aPresContext, nsnull, &child);
+    if (child)
+    { // aFrame is an inline container frame, check my frame state
+      if (childFrameState & NS_INLINE_FRAME_CONTAINS_PERCENT_AWARE_CHILD) {
+        return PR_TRUE;
+      }
+    }
+    // else it's a frame we just don't care about
+  }  
+  return PR_FALSE;
+}
+
+
 void
 nsLineLayout::VerticalAlignFrames(nsLineBox* aLineBox,
                                   nsSize& aMaxElementSizeResult,
@@ -1684,6 +1765,14 @@ nsLineLayout::VerticalAlignFrames(nsLineBox* aLineBox,
       nscoord distanceFromTop = pfd->mBounds.y - mTopEdge;
       PlaceTopBottomFrames(span, distanceFromTop, lineHeight);
     }
+    // check to see if the frame is an inline replace element
+    // and if it is percent-aware.  If so, mark the line.
+    if ((PR_FALSE==aLineBox->ResizeReflowOptimizationDisabled()) &&
+         pfd->mFrameType & NS_CSS_FRAME_TYPE_INLINE)
+    {
+      if (IsPercentageAwareFrame(mPresContext, pfd->mFrame))
+        aLineBox->DisableResizeReflowOptimization();
+    }
     pfd = pfd->mNext;
   }
 
diff --git a/layout/html/base/src/nsLineLayout.h b/layout/html/base/src/nsLineLayout.h
index 38914d0bdd28..d62ee935b315 100644
--- a/layout/html/base/src/nsLineLayout.h
+++ b/layout/html/base/src/nsLineLayout.h
@@ -251,6 +251,12 @@ public:
 
   static PRBool TreatFrameAsBlock(nsIFrame* aFrame);
 
+  static PRBool IsPercentageUnitSides(const nsStyleSides* aSides);
+
+  static PRBool IsPercentageAwareReplacedElement(nsIPresContext *aPresContext, 
+                                                 nsIFrame       *aFrame);
+
+
   //----------------------------------------
 
   nsIPresContext* mPresContext;