Manipulation: Use textarea for missing IE defaultValue check

IE11 fixed the checkbox defaultValue issue but not textarea. Rather than
creating a new detect name I'm reusing the old one to protect anyone who
is unwisely using this externally. Re-fixing the defaultValue when it
doesn't need to be done is not a problem, so leave that code for IE11.

Fixes #14716
Closes gh-1495
Release: Instantiate a zip archiver, run archivers async
Updating the master version to 2.1.1pre.
Build: Upgrade npm devDependencies
Build: Remove obsolete UglifyJS workaround
Tests: Blacklist beforeunload test in iOS

iOS has the window.onbeforeunload field but doesn't support the beforeunload
handler making it impossible to feature-detect the support.

Fixes #14717
Closes gh-1496
Support: Add iOS6 support tests results
Build: Specify browserSets for TestSwarm directly