Support for destructuring assignment

[rmondello]

This:

echo "var [a, b] = [1, 2];" | uglifyJS

Produces:

Parse error at -:1,4
Name expected
Error
    at new JS_Parse_Error (/usr/local/lib/node_modules/uglify-js/lib/parse.js:196:18)
    at js_error (/usr/local/lib/node_modules/uglify-js/lib/parse.js:204:11)
    at croak (/usr/local/lib/node_modules/uglify-js/lib/parse.js:663:9)
    at as_symbol (/usr/local/lib/node_modules/uglify-js/lib/parse.js:1278:27)
    at vardefs (/usr/local/lib/node_modules/uglify-js/lib/parse.js:1070:25)
    at var_ (/usr/local/lib/node_modules/uglify-js/lib/parse.js:1084:27)
    at /usr/local/lib/node_modules/uglify-js/lib/parse.js:825:30
    at /usr/local/lib/node_modules/uglify-js/lib/parse.js:710:24
    at /usr/local/lib/node_modules/uglify-js/lib/parse.js:1446:23
    at Object.parse (/usr/local/lib/node_modules/uglify-js/lib/parse.js:1456:7)

It’d be nice to see this JavaScript 1.7 feature supported in UglifyJS, even behind a flag.

[rvanvelzen]

See #448