JavaScript: destructuring binding with default values

[masatake]

An item not solved in #3435.

If an object literal is specified as a default value in object restructuring, the parser may fail to extract the variable (or constant):

var{ c = {a: 1} } = { c: undefined };
var{ d = {a: 1} } = {d: 3};
var a = 1
var [x0 = {a: 2}, y0] = [, 4];
var [x1 = [a, 2], y`] = [, 4];