Background image should clamp to minimum size(1, 1) after scale.

Source/core/paint/BoxPainter.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/paint/BoxPainter.h"
 
 #include "core/HTMLNames.h"
 #include "core/frame/Settings.h"
 #include "core/html/HTMLFrameOwnerElement.h"
@@ skipping 812 matching lines @@
         if (layerHeight.isFixed())
             tileSize.setHeight(layerHeight.value());
         else if (layerHeight.isPercent())
             tileSize.setHeight(valueForLength(layerHeight, positioningAreaSize.height()));
 
         applySubPixelHeuristicForTileSize(tileSize, positioningAreaSize);
 
         // If one of the values is auto we have to use the appropriate
         // scale to maintain our aspect ratio.
         if (layerWidth.isAuto() && !layerHeight.isAuto()) {
-            if (imageIntrinsicSize.height())
-                tileSize.setWidth(imageIntrinsicSize.width() * tileSize.height() / imageIntrinsicSize.height());
+            if (imageIntrinsicSize.height()) {
+                LayoutUnit adjustedWidth = imageIntrinsicSize.width() * tileSize.height() / imageIntrinsicSize.height();
+                if (imageIntrinsicSize.width() >= 1 && adjustedWidth < 1)
+                    adjustedWidth = 1;
+                tileSize.setWidth(adjustedWidth);
+            }
         } else if (!layerWidth.isAuto() && layerHeight.isAuto()) {
-            if (imageIntrinsicSize.width())
-                tileSize.setHeight(imageIntrinsicSize.height() * tileSize.width() / imageIntrinsicSize.width());
+            if (imageIntrinsicSize.width()) {
+                LayoutUnit adjustedHeight = imageIntrinsicSize.height() * tileSize.width() / imageIntrinsicSize.width();
+                if (imageIntrinsicSize.height() >= 1 && adjustedHeight < 1)
+                    adjustedHeight = 1;
+                tileSize.setHeight(adjustedHeight);
+            }
         } else if (layerWidth.isAuto() && layerHeight.isAuto()) {
             // If both width and height are auto, use the image's intrinsic size.
             tileSize = imageIntrinsicSize;
         }
 
         tileSize.clampNegativeToZero();
         return flooredIntSize(tileSize);
     }
     case SizeNone: {
         // If both values are ‘auto’ then the intrinsic width and/or height of the image should be used, if any.
@@ skipping 1296 matching lines @@
 
     FloatPoint secondQuad[4];
     secondQuad[0] = quad[0];
     secondQuad[1] = FloatPoint(quad[0].x() - r1 * cx, quad[0].y() - r1 * cy);
     secondQuad[2] = quad[2];
     secondQuad[3] = quad[3];
     graphicsContext->clipPolygon(4, secondQuad, !secondEdgeMatches);
 }
 
 } // namespace blink