MO resize restore playback position logic
Merge branch 'develop' of https://github.com/readium/readium-shared-js into develop
no change in functionality, just multi-browser prefixes
fixed TTS for Firefox null vs. undefined woes + fixed jQuery vs. DOM element type
fixed visibility bug, now Media Overlays works in Firefox
fixed iOS HTML5 audio playback bugs (seeking fails sometimes, so the engine is now able to attempt a number of times, then it restarts the asset loading from scratch)
Internet Explorer fix for stale DOMElement.OwnerDocument (SCRIPT70 Permission Denied error)