src/vs/workbench/contrib/snippets/browser/snippetCompletionProvider.ts/SnippetCompletionProvider/_getLanguageIdAtPosition
class SnippetCompletionProvider:	private _getLanguageIdAtPosition(model: ITextModel, position: Position): LanguageId {
		// 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.tokenizeIfCheap(position.lineNumber);
		let languageId = model.getLanguageIdAtPosition(position.lineNumber, position.column);
		const languageIdentifier = this._modeService.getLanguageIdentifier(languageId);
		if (languageIdentifier && !this._modeService.getLanguageName(languageIdentifier.language)) {
			languageId = model.getLanguageIdentifier().id;
		}
		return languageId;
	}