src/vs/editor/common/model/tokenizationTextModelPart.ts/TokenizationTextModelPart/tokenizeViewport
class TokenizationTextModelPart:	public tokenizeViewport(
		startLineNumber: number,
		endLineNumber: number
	): void {
		startLineNumber = Math.max(1, startLineNumber);
		endLineNumber = Math.min(this._textModel.getLineCount(), endLineNumber);
		this._tokenization.tokenizeViewport(startLineNumber, endLineNumber);
	}