For flex items, percent paddings should resolve against their respective dimension

Source/core/rendering/RenderBoxModelObject.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 30 matching lines @@
     BackgroundBleedClipBackground,
     BackgroundBleedBackgroundOverBorder
 };
 
 enum ContentChangeType {
     ImageChanged,
     CanvasChanged,
     CanvasContextChanged
 };
 
+enum PaddingType {
+    TopPadding,
+    RightPadding,
+    BottomPadding,
+    LeftPadding,
+    BeforePadding,
+    AfterPadding,
+    StartPadding,
+    EndPadding
+};
+
 class RenderTextFragment;
 
 // This class is the base for all objects that adhere to the CSS box model as described
 // at http://www.w3.org/TR/CSS21/box.html
 
 class RenderBoxModelObject : public RenderLayerModelObject {
 public:
     RenderBoxModelObject(ContainerNode*);
     virtual ~RenderBoxModelObject();
 
@@ skipping 13 matching lines @@
     int pixelSnappedOffsetTop() const { return roundToInt(offsetTop()); }
     virtual int pixelSnappedOffsetWidth() const;
     virtual int pixelSnappedOffsetHeight() const;
 
     virtual void updateFromStyle() OVERRIDE;
 
     // This will work on inlines to return the bounding box of all of the lines' border boxes.
     virtual IntRect borderBoundingBox() const = 0;
 
     // These return the CSS computed padding values.
-    LayoutUnit computedCSSPaddingTop() const { return computedCSSPadding(style()->paddingTop()); }
-    LayoutUnit computedCSSPaddingBottom() const { return computedCSSPadding(style()->paddingBottom()); }
-    LayoutUnit computedCSSPaddingLeft() const { return computedCSSPadding(style()->paddingLeft()); }
-    LayoutUnit computedCSSPaddingRight() const { return computedCSSPadding(style()->paddingRight()); }
-    LayoutUnit computedCSSPaddingBefore() const { return computedCSSPadding(style()->paddingBefore()); }
-    LayoutUnit computedCSSPaddingAfter() const { return computedCSSPadding(style()->paddingAfter()); }
-    LayoutUnit computedCSSPaddingStart() const { return computedCSSPadding(style()->paddingStart()); }
-    LayoutUnit computedCSSPaddingEnd() const { return computedCSSPadding(style()->paddingEnd()); }
+    LayoutUnit computedCSSPaddingTop() const { return computedCSSPadding(style()->paddingTop(), TopPadding); }
+    LayoutUnit computedCSSPaddingBottom() const { return computedCSSPadding(style()->paddingBottom(), BottomPadding); }
+    LayoutUnit computedCSSPaddingLeft() const { return computedCSSPadding(style()->paddingLeft(), LeftPadding); }
+    LayoutUnit computedCSSPaddingRight() const { return computedCSSPadding(style()->paddingRight(), RightPadding); }
+    LayoutUnit computedCSSPaddingBefore() const { return computedCSSPadding(style()->paddingBefore(), BeforePadding); }
+    LayoutUnit computedCSSPaddingAfter() const { return computedCSSPadding(style()->paddingAfter(), AfterPadding); }
+    LayoutUnit computedCSSPaddingStart() const { return computedCSSPadding(style()->paddingStart(), StartPadding); }
+    LayoutUnit computedCSSPaddingEnd() const { return computedCSSPadding(style()->paddingEnd(), EndPadding); }
 
     // These functions are used during layout. Table cells
     // override them to include some extra intrinsic padding.
     virtual LayoutUnit paddingTop() const { return computedCSSPaddingTop(); }
     virtual LayoutUnit paddingBottom() const { return computedCSSPaddingBottom(); }
     virtual LayoutUnit paddingLeft() const { return computedCSSPaddingLeft(); }
     virtual LayoutUnit paddingRight() const { return computedCSSPaddingRight(); }
     virtual LayoutUnit paddingBefore() const { return computedCSSPaddingBefore(); }
     virtual LayoutUnit paddingAfter() const { return computedCSSPaddingAfter(); }
     virtual LayoutUnit paddingStart() const { return computedCSSPaddingStart(); }
@@ skipping 188 matching lines @@
     void moveChildrenTo(RenderBoxModelObject* toBoxModelObject, RenderObject* startChild, RenderObject* endChild, bool fullRemoveInsert = false)
     {
         moveChildrenTo(toBoxModelObject, startChild, endChild, 0, fullRemoveInsert);
     }
     void moveChildrenTo(RenderBoxModelObject* toBoxModelObject, RenderObject* startChild, RenderObject* endChild, RenderObject* beforeChild, bool fullRemoveInsert = false);
 
     enum ScaleByEffectiveZoomOrNot { ScaleByEffectiveZoom, DoNotScaleByEffectiveZoom };
     IntSize calculateImageIntrinsicDimensions(StyleImage*, const IntSize& scaledPositioningAreaSize, ScaleByEffectiveZoomOrNot) const;
 
 private:
-    LayoutUnit computedCSSPadding(const Length&) const;
+    LayoutUnit computedCSSPadding(const Length&, PaddingType) const;
     virtual bool isBoxModelObject() const OVERRIDE FINAL { return true; }
 
     IntSize calculateFillTileSize(const FillLayer&, const IntSize& scaledPositioningAreaSize) const;
 
+    LayoutUnit containingBlockLogicalHeightForPadding() const;
+
     RoundedRect getBackgroundRoundedRect(const LayoutRect&, InlineFlowBox*, LayoutUnit inlineBoxWidth, LayoutUnit inlineBoxHeight,
         bool includeLogicalLeftEdge, bool includeLogicalRightEdge) const;
 
     bool fixedBackgroundPaintsInLocalCoordinates() const;
 
     void clipBorderSidePolygon(GraphicsContext*, const RoundedRect& outerBorder, const RoundedRect& innerBorder,
                                BoxSide, bool firstEdgeMatches, bool secondEdgeMatches);
     void clipBorderSideForComplexInnerPath(GraphicsContext*, const RoundedRect&, const RoundedRect&, BoxSide, const class BorderEdge[]);
     void paintOneBorderSide(GraphicsContext*, const RenderStyle*, const RoundedRect& outerBorder, const RoundedRect& innerBorder,
                                 const IntRect& sideRect, BoxSide, BoxSide adjacentSide1, BoxSide adjacentSide2, const class BorderEdge[],
                                 const Path*, BackgroundBleedAvoidance, bool includeLogicalLeftEdge, bool includeLogicalRightEdge, bool antialias, const Color* overrideColor = 0);
     void paintTranslucentBorderSides(GraphicsContext*, const RenderStyle*, const RoundedRect& outerBorder, const RoundedRect& innerBorder, const IntPoint& innerBorderAdjustment,
         const class BorderEdge[], BorderEdgeFlags, BackgroundBleedAvoidance, bool includeLogicalLeftEdge, bool includeLogicalRightEdge, bool antialias = false);
     void paintBorderSides(GraphicsContext*, const RenderStyle*, const RoundedRect& outerBorder, const RoundedRect& innerBorder,
         const IntPoint& innerBorderAdjustment, const class BorderEdge[], BorderEdgeFlags, BackgroundBleedAvoidance,
         bool includeLogicalLeftEdge, bool includeLogicalRightEdge, bool antialias = false, const Color* overrideColor = 0);
     void drawBoxSideFromPath(GraphicsContext*, const LayoutRect&, const Path&, const class BorderEdge[],
                             float thickness, float drawThickness, BoxSide, const RenderStyle*,
                             Color, EBorderStyle, BackgroundBleedAvoidance, bool includeLogicalLeftEdge, bool includeLogicalRightEdge);
 };
 
 DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderBoxModelObject, isBoxModelObject());
 
 } // namespace blink
 
 #endif // RenderBoxModelObject_h