v2.53.rc8

• FEC-6423 - HLSJS and Shaka don't respect default audio track setting
• SUP-9661 - playlist player with Iframe embed not playing
• SUP-9286 - Player Button size not saved on Android & Ipad
• FEC-6410 - changeMedia from empty source doesn't play automatically
• FEC-6397 - cvcaa : keyboard shortcuts: clicking on tab key will will cause the X and back icons to disapear . user won't be able to close the cvaa dialog
• FEC-6398 - cvcaa : text in pull down menus is invisible
• FEC-6399 - cvaa: none of the settings affect the captions display
• FEC-6401 - cvaa: the label "custom" is not displayed correctly. the m character is displayed outside of the frame
• update memcache config
• Add default Widevine CDM Robustness level (#3243)
• Revert "ABR enhancements in HLS (#3183)"
• Revert "Add fix in HLS concatenation of URL, (#3226)"