extensions/emmet/src/editPoint.ts/prevEditPoint
function prevEditPoint(selection: vscode.Selection, editor: vscode.TextEditor): vscode.Selection {
	for (let lineNum = selection.anchor.line; lineNum >= 0; lineNum--) {
		let updatedSelection = findEditPoint(lineNum, editor, selection.anchor, 'prev');
		if (updatedSelection) {
			return updatedSelection;
		}
	}
	return selection;
}