Don't let current width affect preferred width on shrink-to-fit containers

third_party/WebKit/Source/core/layout/LayoutBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc.
  *               All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 2732 matching lines @@
       FillAvailableMeasure(available_logical_width, margin_start, margin_end);
 
   if (ShrinkToAvoidFloats() && cb->IsLayoutBlockFlow() &&
       ToLayoutBlockFlow(cb)->ContainsFloats())
     logical_width_result =
         std::min(logical_width_result,
                  ShrinkLogicalWidthToAvoidFloats(margin_start, margin_end,
                                                  ToLayoutBlockFlow(cb)));
 
   if (width_type == kMainOrPreferredSize &&
-      SizesLogicalWidthToFitContent(logical_width))
+      SizesLogicalWidthToFitContent(logical_width)) {
+    // Reset width so that any percent margins on inline children do not
+    // use it when calculating min/max preferred width.
+    // TODO(crbug.com/710026): Remove const_cast
+    const_cast<LayoutBox*>(this)->SetLogicalWidth(LayoutUnit());
     return std::max(MinPreferredLogicalWidth(),
                     std::min(MaxPreferredLogicalWidth(), logical_width_result));
+  }
   return logical_width_result;
 }
 
 bool LayoutBox::ColumnFlexItemHasStretchAlignment() const {
   // auto margins mean we don't stretch. Note that this function will only be
   // used for widths, so we don't have to check marginBefore/marginAfter.
   const auto& parent_style = Parent()->StyleRef();
   DCHECK(parent_style.IsColumnFlexDirection());
   if (StyleRef().MarginStart().IsAuto() || StyleRef().MarginEnd().IsAuto())
     return false;
@@ skipping 3053 matching lines @@
 void LayoutBox::MutableForPainting::
     SavePreviousContentBoxSizeAndLayoutOverflowRect() {
   auto& rare_data = GetLayoutBox().EnsureRareData();
   rare_data.has_previous_content_box_size_and_layout_overflow_rect_ = true;
   rare_data.previous_content_box_size_ = GetLayoutBox().ContentBoxRect().size();
   rare_data.previous_layout_overflow_rect_ =
       GetLayoutBox().LayoutOverflowRect();
 }
 
 }  // namespace blink