I'm not sure if this is an issue with Vscode or with the Tomorrow color theme itself, but there's no repo or issue tracker listed anywhere for the extension, so...

The light version in this color theme:

https://marketplace.visualstudio.com/items/ms-vscode.Theme-TomorrowKit

Results in some code elements being white on the white background:

In this case, the commas and colons in this JSON file.