### Preflight Checklist
* [x] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
* [x] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/CODE_OF_CONDUCT.md) that this project adheres to.
* [x] I have searched the issue tracker for an issue that matches the one I want to file, without success.

### Issue Details
```js
let ret = shell.openItem('file:///noexistent');
console.log(ret);
```
`ret` is always `true` on Linux even if opening fails, e.g.
```sh
xdg-open 'file:///noexistent'
echo $?
```
Shows nonzero error code.

* **Electron Version:**
  * v6.0.11
* **Operating System:**
  *Linux / Ubuntu 16.04 x64

### Expected Behavior
`ret` should be `false`, if `xdg-open` returns non-zero code.

Optional: It would be very nice if the `xdg-open` error (catch stderr) would be displayed in `dialog.showErrorBox` if it returns non-zero code. Just take care that `xdg-open` may write some warnings to stderr even if it returns 0.

shell/common/platform_util_win.cc
public:
  DeleteFileProgressSink();
  virtual ~DeleteFileProgressSink() = default;
 private:
  ULONG STDMETHODCALLTYPE AddRef(void) override;
  ULONG STDMETHODCALLTYPE Release(void) override;
  HRESULT STDMETHODCALLTYPE QueryInterface(REFIID riid,
                                           LPVOID* ppvObj) override;
  HRESULT STDMETHODCALLTYPE StartOperations(void) override;
  HRESULT STDMETHODCALLTYPE FinishOperations(HRESULT) override;
  HRESULT STDMETHODCALLTYPE PreRenameItem(DWORD, IShellItem*, LPCWSTR) override;
  HRESULT STDMETHODCALLTYPE
  PostRenameItem(DWORD, IShellItem*, LPCWSTR, HRESULT, IShellItem*) override;
  HRESULT STDMETHODCALLTYPE PreMoveItem(DWORD,
                                        IShellItem*,
                                        IShellItem*,
                                        LPCWSTR) override;
  HRESULT STDMETHODCALLTYPE PostMoveItem(DWORD,
                                         IShellItem*,
                                         IShellItem*,
                                         LPCWSTR,
                                         HRESULT,
                                         IShellItem*) override;