code: function updateImageSizeCSS(editor, model) {
  	const pos = editor.getCursorBufferPosition();
  	const property = getImageCSSNode(editor, model, pos);
  	const urlToken = findUrlToken(property, pos);
  	const src = urlToken && getImageSrcCSS(urlToken);
  
  	if (!src) {
  		return Promise.reject(new Error('No valid image source'));
  	}
  
  	locateFile(editor, src)
  	.then(getImageSize)
  	.then(size => {
  		// since this action is asynchronous, we have to ensure that editor wasn’t
  		// changed and user didn’t moved caret outside <img> node
  		if (getImageCSSNode(editor, model, pos) === property) {
  			updateCSSNode(editor, property, size.width, size.height);
  		}
  	})
  	.catch(err => console.warn('Error while updating image size:', err));
  }
docs: Updates image size of context rule of stylesheet model
  @param  {TextEditor}  editor
  @param  {SyntaxModel} model
  @return {Promise}