Invoke async method on remote object got by remote.getGlobal causes memory leak.

[imndx]

The following is the test case.

In the test case, after the callback has been called, the arrow function keep been strongly referenced by the remote module，and cannot be gc collected.

// main process

global.foo = {bar: {
        testCallback(cb){
            cb && cb('testCallback');
        }
    }};

// renderer process

let bar = remote.getGlobal('foo').bar;

// create a big array, to make monitor the memory leak easily
let willLeakArray = [];
for (let i = 0; i < 1024 * 1024 * 10; i++) {
    willLeakArray.push('' + i);
}
bar.testCallback((value)=> {
    console.log('testCallback', value, willLeakArray.length ); 
})