src/vs/workbench/contrib/emmet/browser/emmetActions.ts/EmmetEditorAction/_withGrammarContributions
class EmmetEditorAction:	private _withGrammarContributions(extensionService: IExtensionService): Promise<GrammarContributions | null> {
		if (this._lastExtensionService !== extensionService) {
			this._lastExtensionService = extensionService;
			this._lastGrammarContributions = extensionService.readExtensionPointContributions(grammarsExtPoint).then((contributions) => {
				return new GrammarContributions(contributions);
			});
		}
		return this._lastGrammarContributions || Promise.resolve(null);
	}