* Electron Version: 3.0.0-beta.3
* Operating System Ubuntu 18.04
* Last known working Electron version: none  ... still fails on 2.0.5

**Expected Behavior**

Font Subpixel AA should work... only works when rendering a .HTML file, not via BrowserWindow.

**Actual behavior**

Subpixel AA only works when I load a .html file.. not a .js file.

**To Reproduce**

https://github.com/burtonator/electron3-fuzzy-text

Here is a repo.

This works:

```
./node_modules/.bin/electron test.html
```

This will fail:

```
./node_modules/.bin/electron index.js
```
The only way to actually see that it's failing is to use a zoom tool like ```kmag```

**Screenshots**

Here's loading the .html file on the command line. Notice the AA is working by the orange color on the outside of the text:

![image](https://user-images.githubusercontent.com/45447/43037663-8731acd2-8cc4-11e8-99bf-f2adfbfdecc4.png)

Here is the SAME text and same test.html file but I loaded it via BrowserWindow in my index.js script.

![image](https://user-images.githubusercontent.com/45447/43037676-a22fa30e-8cc4-11e8-8bee-4d20bdfde57f.png)

Electron fails to use AA text rendering in the new window.  

Hopefully this might help track down the bug.  


atom/browser/web_contents_preferences.cc
command_line->AppendSwitchASCII(switches::kBackgroundColor, s);
  
  int guest_instance_id = 0;
  if (GetAsInteger(&preference_, options::kGuestInstanceID, &guest_instance_id))
    command_line->AppendSwitchASCII(switches::kGuestInstanceID,
                                    base::IntToString(guest_instance_id));
  
  int opener_id;
  if (GetAsInteger(&preference_, options::kOpenerID, &opener_id))
    command_line->AppendSwitchASCII(switches::kOpenerID,
                                    base::IntToString(opener_id));
#if defined(OS_MACOSX)
  
  if (IsEnabled(options::kScrollBounce))
    command_line->AppendSwitch(switches::kScrollBounce);
#endif
  
  auto* args =
      preference_.FindKeyOfType("commandLineSwitches", base::Value::Type::LIST);
  if (args) {
    for (const auto& arg : args->GetList()) {
      if (arg.is_string()) {
        const auto& arg_val = arg.GetString();
        if (!arg_val.empty())
          command_line->AppendSwitch(arg_val);
      }
    }
  }
  
  if (GetAsString(&preference_, options::kEnableBlinkFeatures, &s))