Allen Wirfs-Brock (2013-09-24T18:58:38.000Z)
domenic at domenicdenicola.com (2013-09-25T18:48:38.686Z)
It is an early error, which is specified via the "IsValidSinpleAssigment" based Early Error rules in http://people.mozilla.org/~jorendorff/es6-draft.html#sec-12.13.1 This follows from the ES5 requirement in clause 16: that says "Attempts to PutValue on any value for which early determination can be made that the value is not a Reference" [is an early error]. IsValidSimpleAssignmentTarget is a formalization of that "early determination".