Fix underline/overline flipping

third_party/WebKit/Source/core/paint/InlineTextBoxPainter.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 "core/paint/InlineTextBoxPainter.h"
 
 #include "core/editing/Editor.h"
 #include "core/editing/markers/CompositionMarker.h"
 #include "core/editing/markers/DocumentMarkerController.h"
 #include "core/editing/markers/TextMatchMarker.h"
@@ skipping 201 matching lines @@
   ResolvedUnderlinePosition underline_position =
       decoration_info.underline_position;
   bool flip_underline_and_overline = false;
   if (underline_position == ResolvedUnderlinePosition::kOver) {
     flip_underline_and_overline = true;
     underline_position = ResolvedUnderlinePosition::kUnder;
   }
 
   for (const AppliedTextDecoration& decoration : decorations) {
     TextDecoration lines = decoration.Lines();
+    bool has_underline = EnumHasFlags(lines, TextDecoration::kUnderline);
+    bool has_overline = EnumHasFlags(lines, TextDecoration::kOverline);
     if (flip_underline_and_overline) {
-      lines ^= (TextDecoration::kUnderline | TextDecoration::kOverline);
+      std::swap(has_underline, has_overline);
     }
-    if (EnumHasFlags(lines, TextDecoration::kUnderline) &&
-        decoration_info.font_data) {
+    if (has_underline && decoration_info.font_data) {
       const int underline_offset = ComputeUnderlineOffset(
           underline_position, *decoration_info.style,
           decoration_info.font_data->GetFontMetrics(), &box, decorating_box,
           decoration_info.thickness);
       text_painter.PaintDecorationUnderOrOverLine(
           context, decoration_info, decoration, underline_offset,
           decoration_info.double_offset);
     }
-    if (EnumHasFlags(lines, TextDecoration::kOverline)) {
+    if (has_overline) {
       const int overline_offset = ComputeUnderlineOffsetForUnder(
           *decoration_info.style, &box, decorating_box,
           decoration_info.thickness,
           flip_underline_and_overline ? LineVerticalPositionType::TopOfEmHeight
                                       : LineVerticalPositionType::TextTop);
       text_painter.PaintDecorationUnderOrOverLine(
           context, decoration_info, decoration, overline_offset,
           -decoration_info.double_offset);
     }
     // We could instead build a vector of the TextDecoration instances needing
@@ skipping 932 matching lines @@
 
   LayoutRect box_rect(box_origin, LayoutSize(inline_text_box_.LogicalWidth(),
                                              inline_text_box_.LogicalHeight()));
   context.Clip(FloatRect(box_rect));
   context.DrawHighlightForText(font, run, FloatPoint(box_origin),
                                box_rect.Height().ToInt(), color,
                                paint_offsets.first, paint_offsets.second);
 }
 
 }  // namespace blink