Keep the selection of the text field when changed by JS.

Source/core/editing/FrameSelection.cpp

Index: Source/core/editing/FrameSelection.cpp
diff --git a/Source/core/editing/FrameSelection.cpp b/Source/core/editing/FrameSelection.cpp
index 4fd0cea2362ac909447b0962c26762f0afbc6751..409872d29035114f0dc96234b178d751e3814d75 100644
--- a/Source/core/editing/FrameSelection.cpp
+++ b/Source/core/editing/FrameSelection.cpp
@@ -299,6 +299,7 @@ void FrameSelection::setSelection(const VisibleSelection& newSelection, SetSelec
 
     notifyAccessibilityForSelectionChange();
     notifyCompositorForSelectionChange();
+    notifyEventHandlerForSelectionChange();
     m_frame->localDOMWindow()->enqueueDocumentEvent(Event::create(EventTypeNames::selectionchange));
 }
 
@@ -1460,6 +1461,11 @@ void FrameSelection::notifyCompositorForSelectionChange()
     scheduleVisualUpdate();
 }
 
+void FrameSelection::notifyEventHandlerForSelectionChange()
+{
+    m_frame->eventHandler().notifySelectionChanged();
+}
+
 void FrameSelection::focusedOrActiveStateChanged()
 {
     bool activeAndFocused = isFocusedAndActive();