src/vs/editor/common/model/textModelTokens.ts/TextModelTokenization/_beginBackgroundTokenization
class TextModelTokenization:	private _beginBackgroundTokenization(): void {
		if (this._isScheduled || !this._textModel.isAttachedToEditor() || !this._hasLinesToTokenize()) {
			return;
		}

		this._isScheduled = true;
		runWhenIdle((deadline) => {
			this._isScheduled = false;

			this._backgroundTokenizeWithDeadline(deadline);
		});
	}