- Electron version: 1.4.0
- Operating system: OS X 10.10.5

I've been using the following code to send Tab key events to a webview in my project:

``` js
const webContents = webView.getWebContents();
const keyEvent = {
  type: 'keyDown',
  keyCode: 'Tab'
};

webContents.sendInputEvent(keyEvent);
```

I have had no issues with this until the recent update to 1.4.0.

The last version the above code works in OS X is **1.3.7**. I've tried this with the latest versions of Electron (1.4.1 & 1.4.2) with the same results.

Am I doing something wrong here? Is this a known issue?

atom/common/keyboard_util.cc
bool* shifted) {
  std::string str = base::ToLowerASCII(s);
  if (str == "ctrl" || str == "control") {
    return ui::VKEY_CONTROL;
  } else if (str == "super" || str == "cmd" || str == "command" ||
             str == "meta") {
    return ui::VKEY_COMMAND;
  } else if (str == "commandorcontrol" || str == "cmdorctrl") {
#if defined(OS_MACOSX)
    return ui::VKEY_COMMAND;
#else
    return ui::VKEY_CONTROL;
#endif
  } else if (str == "alt" || str == "option") {
    return ui::VKEY_MENU;
  } else if (str == "shift") {
    return ui::VKEY_SHIFT;
  } else if (str == "altgr") {
    return ui::VKEY_ALTGR;
  } else if (str == "plus") {
    *shifted = true;
    return ui::VKEY_OEM_PLUS;
  } else if (str == "tab") {
    return ui::VKEY_TAB;
  } else if (str == "space") {