Remove frame flattening support as Chromium has no intention of using it

Source/core/rendering/RenderFrameSet.cpp

Index: Source/core/rendering/RenderFrameSet.cpp
diff --git a/Source/core/rendering/RenderFrameSet.cpp b/Source/core/rendering/RenderFrameSet.cpp
index 7f248d1730b418faefdaea8655b7ec2c45c16eb2..cca4291a5590e01086f8623e1a57bff0dc1eece8 100644
--- a/Source/core/rendering/RenderFrameSet.cpp
+++ b/Source/core/rendering/RenderFrameSet.cpp
@@ -471,10 +471,7 @@ void RenderFrameSet::layout()
     layOutAxis(m_rows, frameSet()->rowLengths(), height() - (rows - 1) * borderThickness);
     layOutAxis(m_cols, frameSet()->colLengths(), width() - (cols - 1) * borderThickness);
 
-    if (flattenFrameSet())
-        positionFramesWithFlattening();
-    else
-        positionFrames();
+    positionFrames();
 
     RenderBox::layout();
 
@@ -535,119 +532,6 @@ void RenderFrameSet::positionFrames()
     }
 }
 
-void RenderFrameSet::positionFramesWithFlattening()
-{
-    RenderBox* child = firstChildBox();
-    if (!child)
-        return;
-
-    int rows = frameSet()->totalRows();
-    int cols = frameSet()->totalCols();
-
-    int borderThickness = frameSet()->border();
-    bool repaintNeeded = false;
-
-    // calculate frameset height based on actual content height to eliminate scrolling
-    bool out = false;
-    for (int r = 0; r < rows && !out; r++) {
-        int extra = 0;
-        int height = m_rows.m_sizes[r];
-
-        for (int c = 0; c < cols; c++) {
-            IntRect oldFrameRect = pixelSnappedIntRect(child->frameRect());
-
-            int width = m_cols.m_sizes[c];
-
-            bool fixedWidth = frameSet()->colLengths() && frameSet()->colLengths()[c].isFixed();
-            bool fixedHeight = frameSet()->rowLengths() && frameSet()->rowLengths()[r].isFixed();
-
-            // has to be resized and itself resize its contents
-            if (!fixedWidth)
-                child->setWidth(width ? width + extra / (cols - c) : 0);
-            else
-                child->setWidth(width);
-            child->setHeight(height);
-
-            child->setNeedsLayout(true);
-
-            if (child->isFrameSet())
-                toRenderFrameSet(child)->layout();
-            else
-                toRenderFrame(child)->layoutWithFlattening(fixedWidth, fixedHeight);
-
-            if (child->height() > m_rows.m_sizes[r])
-                m_rows.m_sizes[r] = child->height();
-            if (child->width() > m_cols.m_sizes[c])
-                m_cols.m_sizes[c] = child->width();
-
-            if (child->frameRect() != oldFrameRect)
-                repaintNeeded = true;
-
-            // difference between calculated frame width and the width it actually decides to have
-            extra += width - m_cols.m_sizes[c];
-
-            child = child->nextSiblingBox();
-            if (!child) {
-                out = true;
-                break;
-            }
-        }
-    }
-
-    int xPos = 0;
-    int yPos = 0;
-    out = false;
-    child = firstChildBox();
-    for (int r = 0; r < rows && !out; r++) {
-        xPos = 0;
-        for (int c = 0; c < cols; c++) {
-            // ensure the rows and columns are filled
-            IntRect oldRect = pixelSnappedIntRect(child->frameRect());
-
-            child->setLocation(IntPoint(xPos, yPos));
-            child->setHeight(m_rows.m_sizes[r]);
-            child->setWidth(m_cols.m_sizes[c]);
-
-            if (child->frameRect() != oldRect) {
-                repaintNeeded = true;
-
-                // update to final size
-                child->setNeedsLayout(true);
-                if (child->isFrameSet())
-                    toRenderFrameSet(child)->layout();
-                else
-                    toRenderFrame(child)->layoutWithFlattening(true, true);
-            }
-
-            xPos += m_cols.m_sizes[c] + borderThickness;
-            child = child->nextSiblingBox();
-            if (!child) {
-                out = true;
-                break;
-            }
-        }
-        yPos += m_rows.m_sizes[r] + borderThickness;
-    }
-
-    setWidth(xPos - borderThickness);
-    setHeight(yPos - borderThickness);
-
-    if (repaintNeeded)
-        repaint();
-
-    // all the remaining frames are hidden to avoid ugly spurious unflowed frames
-    for (; child; child = child->nextSiblingBox()) {
-        child->setWidth(0);
-        child->setHeight(0);
-        child->setNeedsLayout(false);
-    }
-}
-
-bool RenderFrameSet::flattenFrameSet() const
-{
-    return frame() && frame()->settings() && frame()->settings()->frameFlatteningEnabled();
-}
-
 void RenderFrameSet::startResizing(GridAxis& axis, int position)
 {
     int split = hitTestSplit(axis, position);
@@ -676,9 +560,6 @@ void RenderFrameSet::continueResizing(GridAxis& axis, int position)
 
 bool RenderFrameSet::userResize(MouseEvent* evt)
 {
-    if (flattenFrameSet())
-        return false;
-
     if (!m_isResizing) {
         if (needsLayout())
             return false;