src/vs/workbench/contrib/snippets/browser/snippetCompletionProvider.ts/SnippetCompletionProvider/_getLanguageIdAtPosition
class SnippetCompletionProvider:	private _getLanguageIdAtPosition(model: ITextModel, position: Position): string {
		// validate the `languageId` to ensure this is a user
		// facing language with a name and the chance to have
		// snippets, else fall back to the outer language
		model.tokenization.tokenizeIfCheap(position.lineNumber);
		let languageId = model.getLanguageIdAtPosition(position.lineNumber, position.column);
		if (!this._languageService.getLanguageName(languageId)) {
			languageId = model.getLanguageId();
		}
		return languageId;
	}