[Experiment] DCHECK clean layout tree in mostForward/BackwardCaretPosition

third_party/WebKit/Source/core/editing/FrameSelection.cpp

Index: third_party/WebKit/Source/core/editing/FrameSelection.cpp
diff --git a/third_party/WebKit/Source/core/editing/FrameSelection.cpp b/third_party/WebKit/Source/core/editing/FrameSelection.cpp
index 78531bc8f80f3948c0b7bd0d6986fe61fb913ea2..4a80c7457bdd09213d5cd2456a3985e85d2114a5 100644
--- a/third_party/WebKit/Source/core/editing/FrameSelection.cpp
+++ b/third_party/WebKit/Source/core/editing/FrameSelection.cpp
@@ -78,6 +78,7 @@
 #include "platform/geometry/FloatQuad.h"
 #include "platform/graphics/GraphicsContext.h"
 #include "platform/text/UnicodeUtilities.h"
+#include "wtf/AutoReset.h"
 #include "wtf/PtrUtil.h"
 #include "wtf/text/CString.h"
 #include <stdio.h>
@@ -590,6 +591,8 @@ void FrameSelection::updateSelectionIfNeeded(const Position& base,
                                              const Position& extent,
                                              const Position& start,
                                              const Position& end) {
+  AutoReset<bool> scope(&m_inUpdateSelectionIfNeeded, true);
+
   if (base == selection().base() && extent == selection().extent() &&
       start == selection().start() && end == selection().end())
     return;