src/vs/editor/common/model/tokenizationTextModelPart.ts/TokenizationTextModelPart/getLanguageIdAtPosition
class TokenizationTextModelPart:	public getLanguageIdAtPosition(lineNumber: number, column: number): string {
		const position = this._textModel.validatePosition(new Position(lineNumber, column));
		const lineTokens = this.getLineTokens(position.lineNumber);
		return lineTokens.getLanguageId(lineTokens.findTokenIndexAtOffset(position.column - 1));
	}