src/vs/editor/standalone/common/monarch/monarchLexer.ts/MonarchTokenizer/_getNestedEmbeddedModeData
class MonarchTokenizer:	private _getNestedEmbeddedModeData(mimetypeOrModeId: string): EmbeddedModeData {
		let nestedModeId = this._locateMode(mimetypeOrModeId);
		if (nestedModeId) {
			let tokenizationSupport = modes.TokenizationRegistry.get(nestedModeId);
			if (tokenizationSupport) {
				return new EmbeddedModeData(nestedModeId, tokenizationSupport.getInitialState());
			}
		}

		return new EmbeddedModeData(nestedModeId || NULL_MODE_ID, NULL_STATE);
	}