Fix #6458 - crash in BTextView when entering Japanese characters

* when I changed InsertText() to adjust the caret position recently, I
  forgot to drop that adjustment from all callers - _HandleInputMethodChanged()
  was still doing it, leading to out of bounds access

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@38243 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/kits/interface/TextView.cpp

@@ -5401,8 +5401,6 @@ BTextView::_HandleInputMethodChanged(BMessage *message)
 
 		const int32 inlineOffset = fInline->Offset();
 		InsertText(string, stringLen, fSelStart, NULL);
-		fSelStart += stringLen;
-		fCaretOffset = fSelEnd = fSelStart;
 
 		_Refresh(inlineOffset, fSelEnd, true);
 		_ShowCaret();