Bug 1273510 part.2 Modify comment in IMMHandler::SetCandidateWindow() r=m_kato

MozReview-Commit-ID: KX1frgDFsPi

--HG--
extra : rebase_source : e8478a5d61b68e01b2b7bce34705273d8a891e11

widget/windows/IMMHandler.cpp

@@ -2756,8 +2756,9 @@ IMMHandler::OnKeyDownEvent(nsWindow* aWindow,
 void
 IMMHandler::SetCandidateWindow(nsWindow* aWindow, CANDIDATEFORM* aForm)
 {
-  // Hack for ATOK.  ATOK (Japanese IME) refers native caret position at
-  // deciding candidate window position.
+  // Hack for ATOK 2011 - 2016 (Japanese IME).  They refer native caret
+  // position at deciding candidate window position.  Note that we cannot
+  // check active IME since TIPs are wrapped and hidden by CUAS.
   if (aWindow->PluginHasFocus()) {
     // We cannot retrieve proper character height from plugin.  Therefore,
     // we should assume that the caret height is always 20px since if less than