* 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
auto* fonts_dict = preference_.FindKeyOfType("defaultFontFamily",
                                               base::Value::Type::DICTIONARY);
  if (fonts_dict) {
    base::string16 font;
    if (GetAsString(fonts_dict, "standard", &font))
      prefs->standard_font_family_map[content::kCommonScript] = font;
    if (GetAsString(fonts_dict, "serif", &font))
      prefs->serif_font_family_map[content::kCommonScript] = font;
    if (GetAsString(fonts_dict, "sansSerif", &font))
      prefs->sans_serif_font_family_map[content::kCommonScript] = font;
    if (GetAsString(fonts_dict, "monospace", &font))
      prefs->fixed_font_family_map[content::kCommonScript] = font;
    if (GetAsString(fonts_dict, "cursive", &font))
      prefs->cursive_font_family_map[content::kCommonScript] = font;
    if (GetAsString(fonts_dict, "fantasy", &font))
      prefs->fantasy_font_family_map[content::kCommonScript] = font;
  }
  int size;
  if (GetAsInteger(&preference_, "defaultFontSize", &size))
    prefs->default_font_size = size;
  if (GetAsInteger(&preference_, "defaultMonospaceFontSize", &size))
    prefs->default_fixed_font_size = size;
  if (GetAsInteger(&preference_, "minimumFontSize", &size))
    prefs->minimum_font_size = size;
  std::string encoding;
  if (GetAsString(&preference_, "defaultEncoding", &encoding))
    prefs->default_encoding = encoding;
}
}