Extension initialisation broken for Chrome 51

Environment

• Windows 10 or Debian testing
• Chrome 51
• Adblock Plus equiv of dev build 3.6.3.2388.

How to reproduce

Install the extension and open the background console.

Observed behaviour

• First-run page doesn't open.
• Some default filter lists are not installed.
• One of the following exceptions is displayed in the background console:

uninstall.js:66 Uncaught (in promise) TypeError: Iterator result undefined is not an object(…)

subscriptionInit.js:85 Uncaught (in promise) TypeError: Iterator result undefined is not an object(…)

Expected behaviour

• First-run page opens.
• All default filter lists are installed.
• No error in JavaScript console.

What to change

Increase the minimum supported version of Chrome to 52 and Opera to 39.

Notes

• Regression introduced with 7b3d1090 (see trac#7302
• Issue is not present on Chrome 52.
• The problem seems to be caused by Chromium issue 5057. Chrome 51 has a bug whereby if you break out of a "for ... of generator" loop early this exception is thrown.
• The problem is likely unrealistic to workaround, see this comment.
• Related UI issues adblockplusui#583, adblockplusui#584, adblockplusui#585, adblockplusui#586 and adblockplusui#587.

Hints for testers

• Please start testing with Chrome 52 and Opera 39 as they are now the minimum supported versions.