split ttsNextChunk() into two phases, pre and post-flip animation.
split ttsNextChunk() into two phases, pre and post-flip animation.

internetarchive/bookreader,yankl/bookreader,yankl/bookreader,openlibrary/bookreader,Islandora/internet_archive_bookreader,nikolas/bookreader,garyrh/bookreader,brisandbeans/bookreader,yankl/bookreader,Islandora/internet_archive_bookreader,garyrh/bookreader,nikolas/bookreader,openlibrary/bookreader,yankl/bookreader,garyrh/bookreader,brisandbeans/bookreader,Islandora/internet_archive_bookreader,niksu/bookreader,brisandbeans/bookreader,gootdude/bookreader,brisandbeans/bookreader,niksu/bookreader,gootdude/bookreader,openlibrary/bookreader,gootdude/bookreader,yankl/bookreader,niksu/bookreader,internetarchive/bookreader,gootdude/bookreader,Islandora/internet_archive_bookreader,openlibrary/bookreader,garyrh/bookreader,niksu/bookreader,garyrh/bookreader,openlibrary/bookreader,brisandbeans/bookreader,niksu/bookreader,Islandora/internet_archive_bookreader