Revert of Remove ClearSelection() from Layout{BlockFlow,Inline}::WillbeDestroyed()

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

Index: third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp b/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
index 9fd14255efb568cc83fcfc7da64129b8aba15919..344c09729556d43bca860682ff1c9790dd5c16de 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
@@ -2827,6 +2827,13 @@
     // TODO(mstensho): figure out if we need this. We have no test coverage for
     // it. It looks like all line boxes have been removed at this point.
     if (FirstLineBox()) {
+      // We can't wait for LayoutBox::destroy to clear the selection,
+      // because by then we will have nuked the line boxes.
+      // FIXME: The FrameSelection should be responsible for this when it
+      // is notified of DOM mutations.
+      if (IsSelectionBorder())
+        View()->ClearSelection();
+
       // If we are an anonymous block, then our line boxes might have children
       // that will outlast this block. In the non-anonymous block case those
       // children will be destroyed by the time we return from this function.