Cannot generate top level function from global assignment expression in SequenceExpression

[fossamagna]

Expected Behavior

Input source code:

function a() {
}
function b() {
}
global.a =a, global.b = b;

expected generated code:

function a() {
}
function b() {
}

Actual Behavior

actual generated code is emtpy.

See fossamagna/gas-webpack-plugin#208