extensions/merge-conflict/src/mergeDecorator.ts/MergeDecorator/removeDecorations
class MergeDecorator:	private removeDecorations(editor: vscode.TextEditor) {
		// Remove all decorations, there might be none
		Object.keys(this.decorations).forEach(decorationKey => {

			// Race condition, while editing the settings, it's possible to
			// generate regions before the configuration has been refreshed
			const decorationType = this.decorations[decorationKey];

			if (decorationType) {
				editor.setDecorations(decorationType, []);
			}
		});
	}