[bug] Redefining live function & class bindings

[Andarist]

REPL url

Input

export function foo() { }
foo = 'bar'

expected output

'use strict';

Object.defineProperty(exports, '__esModule', { value: true });

function foo() { }
exports.foo = foo;
exports.foo = 'bar';

actual output

'use strict';

Object.defineProperty(exports, '__esModule', { value: true });

function exports.foo() { }
exports.foo = 'bar';

From what I see rollup@0.49 hadnt this bug, it had different one though - wrong value was preserved on the exports.

I've found this when experimenting with experimentalCodeSplitting which caused babelHelpers.extends to be put in chunk1.js and it is implemented in this "redefining" style (to support uglifyjs DCE) which broke my build.

[lukastaegert]

As I'm currently reworking larger parts of the rendering logic I'll have a look at this one as well.