Fontsize whitelist

[JohnMusleh]

Is there a way to whitelist font sizes?

I have a delta object like this:

... {
                "insert": "test",
                "attributes": {
                    "bold": true,
                    "size": "10px",
                    "color": "#ffffff"
                }
  }

I expect an output like this:

<span style="color: #ffffff; font-size:10px">test</span>

However, I'm getting:

<span style="color: #ffffff">test</span>

Any way I can solve this?