Get rid of a redundant argument DOWNSTREAM from VisiblePosition constructor call sites

Source/core/editing/commands/InsertTextCommand.cpp

Index: Source/core/editing/commands/InsertTextCommand.cpp
diff --git a/Source/core/editing/commands/InsertTextCommand.cpp b/Source/core/editing/commands/InsertTextCommand.cpp
index 50f2c14da72d26b20ef3f98748ba9d519bc295ef..0e4d680553597ad0a07a852eaf02684fe98577a4 100644
--- a/Source/core/editing/commands/InsertTextCommand.cpp
+++ b/Source/core/editing/commands/InsertTextCommand.cpp
@@ -231,7 +231,7 @@ void InsertTextCommand::doApply()
 
 Position InsertTextCommand::insertTab(const Position& pos)
 {
-    Position insertPos = VisiblePosition(pos, DOWNSTREAM).deepEquivalent();
+    Position insertPos = VisiblePosition(pos).deepEquivalent();
     if (insertPos.isNull())
         return pos;