Theme.name does not match registered name

[BeksOmega]

Describe the bug

When you create a new theme that is not entirely lowercase, the .name property of the theme does not match the name in the registry. The registry normalizes all names to lowercase, but the themes are not doing this.

To Reproduce

Steps to reproduce the behavior:

1. Open the playground source.
2. Edit the start function to include:

const theme = Blockly.Theme.defineTheme('TEST', {});
console.log(theme);
console.log(Blockly.registry.getAllItems(Blockly.registry.Type.THEME));

3. Observe how the theme has the name 'TEST', but the item has the key 'test'

Expected behavior

The theme should also have the name 'test'

Additional context

This was found when Greg attempted to define a non-lowercase theme in the advanced playground.

[cpcallen]

Is there some reason that the registry normalises to lowercase? To me that seems like the bug…

[BeksOmega]

Closed by #6226