evita: views: Fix source doe layout in "evita/views/window.{cc,h}".
evita: views: Use one of |virtual/override/final| in "evita/vi_EditPane.cc".
evita: views/tabs: Defer |Tab| realization at update layout.
evita/gfx: Check parameters for |gfx::TextFormat::CreateTextLayout()|.
common: Make destructor of |common::Singleton<T>| as |virtual|.
evita: views/tabs: Use one of |virtual/override/final| in "evita/views/tabs/tab_strip.{cc,h}".
evita: views: Don't create |gfx::TextLayout| object for empty part.