focus() behaviour differs depending on how value is set

Source/core/html/HTMLTextFormControlElement.h

Index: Source/core/html/HTMLTextFormControlElement.h
diff --git a/Source/core/html/HTMLTextFormControlElement.h b/Source/core/html/HTMLTextFormControlElement.h
index 0aa120b67b37c101a0e2af7a7ffc1bb05f3248cb..576c867f86d1cc426354eebe492b319dd837e699 100644
--- a/Source/core/html/HTMLTextFormControlElement.h
+++ b/Source/core/html/HTMLTextFormControlElement.h
@@ -95,13 +95,13 @@ protected:
 
     void cacheSelection(int start, int end, TextFieldSelectionDirection direction)
     {
+        ASSERT(start >= 0);
         m_cachedSelectionStart = start;
         m_cachedSelectionEnd = end;
         m_cachedSelectionDirection = direction;
     }
 
     void restoreCachedSelection();
-    bool hasCachedSelection() const { return m_cachedSelectionStart >= 0; }
 
     virtual void defaultEventHandler(Event*) OVERRIDE;
     virtual void subtreeHasChanged() = 0;