ember-source 3.8.0-beta.1 on Node.js NPM

#17143 / #17375 [FEATURE] Implement Element Modifier Manager RFC (see emberjs/rfcs#0373).
#17054 / #17376 [FEATURE] Implement array helper RFC (see emberjs/rfcs#0318)
#16735 [BUGFIX] Observed properties not being marked as enum
#17319 [CLEANUP] Remove deprecated 'POSITIONAL_PARAM_CONFLICT'
#17394 [CLEANUP] Remove deprecated code in mixins/array
#17166 Improve performance of get() / set()
#16710 Deprecation of (private) NAME_KEY
#17244 Upgrade to Glimmer VM 0.37.0
#17216 Use native Error instead of custom Error subclass.
#17340 Remove unused hooks variable from qunit-rfc-232 util-test blueprint
#17357 Allow notifyPropertyChange to be imported from @ember/object
#17413 Fix missing import in instance-initializer blueprint for ember-mocha

ember-source 3.8.0-beta.1 v3.8.0-beta.1 on Node.js NPM