Blink does not respect input.selectionStart and input.selectionEnd for some cases

Source/core/html/HTMLTextFormControlElement.cpp

Index: Source/core/html/HTMLTextFormControlElement.cpp
diff --git a/Source/core/html/HTMLTextFormControlElement.cpp b/Source/core/html/HTMLTextFormControlElement.cpp
index c3f751a63f54d4eb643bdb97275b0ecbe1ae555c..816371b5a1c49296f951c303d8cb7eba837d3125 100644
--- a/Source/core/html/HTMLTextFormControlElement.cpp
+++ b/Source/core/html/HTMLTextFormControlElement.cpp
@@ -164,12 +164,12 @@ void HTMLTextFormControlElement::updatePlaceholderVisibility(bool placeholderVal
 
 void HTMLTextFormControlElement::setSelectionStart(int start)
 {
-    setSelectionRange(start, max(start, selectionEnd()), selectionDirection());
+    setSelectionRange(start, max(start, selectionEndForJavascriptBindings()), selectionDirection());
 }
 
 void HTMLTextFormControlElement::setSelectionEnd(int end)
 {
-    setSelectionRange(min(end, selectionStart()), end, selectionDirection());
+    setSelectionRange(min(end, selectionStartForJavascriptBindings()), end, selectionDirection());
 }
 
 void HTMLTextFormControlElement::setSelectionDirection(const String& direction)
@@ -279,11 +279,10 @@ void HTMLTextFormControlElement::setSelectionRange(int start, int end, TextField
 
     end = max(end, 0);
     start = min(max(start, 0), end);
+    cacheSelection(start, end, direction);
 
-    if (!hasVisibleTextArea(renderer(), innerTextElement())) {
-        cacheSelection(start, end, direction);
+    if (!hasVisibleTextArea(renderer(), innerTextElement()))
         return;
-    }
     VisiblePosition startPosition = visiblePositionForIndex(start);
     VisiblePosition endPosition;
     if (start == end)
@@ -335,6 +334,20 @@ int HTMLTextFormControlElement::selectionStart() const
 {
     if (!isTextFormControl())
         return 0;
+    if (document().focusedElement() != this) {
+        int innerTextLength = innerTextValue().length();
+        if (innerTextLength < m_cachedSelectionStart)
+            return innerTextLength;
+        return m_cachedSelectionStart;
+    }
+
+    return computeSelectionStart();
+}
+
+int HTMLTextFormControlElement::selectionStartForJavascriptBindings() const
+{
+    if (!isTextFormControl())
+        return 0;
     if (document().focusedElement() != this)
         return m_cachedSelectionStart;
 
@@ -355,8 +368,22 @@ int HTMLTextFormControlElement::selectionEnd() const
 {
     if (!isTextFormControl())
         return 0;
+    if (document().focusedElement() != this) {
+        int innerTextLength = innerTextValue().length();
+        if (innerTextLength < m_cachedSelectionEnd)
+            return innerTextLength;
+        return m_cachedSelectionEnd;
+    }
+    return computeSelectionEnd();
+}
+
+int HTMLTextFormControlElement::selectionEndForJavascriptBindings() const
+{
+    if (!isTextFormControl())
+        return 0;
     if (document().focusedElement() != this)
         return m_cachedSelectionEnd;
+
     return computeSelectionEnd();
 }
 
@@ -472,9 +499,6 @@ void HTMLTextFormControlElement::selectionChanged(bool userTriggered)
     if (!renderer() || !isTextFormControl())
         return;
 
-    // selectionStart() or selectionEnd() will return cached selection when this node doesn't have focus
-    cacheSelection(computeSelectionStart(), computeSelectionEnd(), computeSelectionDirection());
-
     if (LocalFrame* frame = document().frame()) {
         if (frame->selection().isRange() && userTriggered)
             dispatchEvent(Event::createBubble(EventTypeNames::select));