Remove some dead code from rendering/ folder

Source/core/rendering/RenderFlexibleBox.cpp

Index: Source/core/rendering/RenderFlexibleBox.cpp
diff --git a/Source/core/rendering/RenderFlexibleBox.cpp b/Source/core/rendering/RenderFlexibleBox.cpp
index 732534714a7bd2ee4802b29946d412e7c0aaf92e..9ed21c42c6a42dba8a5fdf780c2809c1aba72cba 100644
--- a/Source/core/rendering/RenderFlexibleBox.cpp
+++ b/Source/core/rendering/RenderFlexibleBox.cpp
@@ -377,14 +377,6 @@ Length RenderFlexibleBox::flexBasisForChild(RenderBox* child) const
     return flexLength;
 }
 
-void RenderFlexibleBox::setCrossAxisExtent(LayoutUnit extent)
-{
-    if (isHorizontalFlow())
-        setHeight(extent);
-    else
-        setWidth(extent);
-}
-
 LayoutUnit RenderFlexibleBox::crossAxisExtentForChild(RenderBox* child) const
 {
     return isHorizontalFlow() ? child->height() : child->width();
@@ -578,22 +570,6 @@ LayoutUnit RenderFlexibleBox::flowAwareMarginBeforeForChild(RenderBox* child) co
     return marginTop();
 }
 
-LayoutUnit RenderFlexibleBox::flowAwareMarginAfterForChild(RenderBox* child) const
-{
-    switch (transformedWritingMode()) {
-    case TopToBottomWritingMode:
-        return child->marginBottom();
-    case BottomToTopWritingMode:
-        return child->marginTop();
-    case LeftToRightWritingMode:
-        return child->marginRight();
-    case RightToLeftWritingMode:
-        return child->marginLeft();
-    }
-    ASSERT_NOT_REACHED();
-    return marginBottom();
-}
-
 LayoutUnit RenderFlexibleBox::crossAxisMarginExtentForChild(RenderBox* child) const
 {
     return isHorizontalFlow() ? child->marginHeight() : child->marginWidth();
@@ -622,11 +598,6 @@ LayoutUnit RenderFlexibleBox::mainAxisBorderAndPaddingExtentForChild(RenderBox*
     return isHorizontalFlow() ? child->borderAndPaddingWidth() : child->borderAndPaddingHeight();
 }
 
-LayoutUnit RenderFlexibleBox::mainAxisScrollbarExtentForChild(RenderBox* child) const
-{
-    return isHorizontalFlow() ? child->verticalScrollbarWidth() : child->horizontalScrollbarHeight();
-}
-
 static inline bool preferredMainAxisExtentDependsOnLayout(const Length& flexBasis, bool hasInfiniteLineLength)
 {
     return flexBasis.isAuto() || (flexBasis.isFixed() && !flexBasis.value() && hasInfiniteLineLength);