First, it doesn't look like your angular.module code is inside a script tag. Also, try conditionally including the module, or conditionally loading a different "app" module (one that does not require this dependency):
Conditional script include
<!--[if lt IE 9]><!-->
<script type="text/javascript">angular.module('bootstrapLightbox', []);</script>
<!--<![endif]-->
<!--[if (gt IE 9)|!(IE)]><!-->
<script src="bower_components/angular-bootstrap-lightbox/dist/angular-bootstrap-lightbox.js"></script>
<!--<![endif]-->
Conditional app module load
<!--[if lt IE 9]><!-->
<html ng-app="myLegacyIEAppModule">
<!--<![endif]-->
<!--[if (gt IE 9)|!(IE)]><!-->
<html ng-app="myAppModuleForEveryoneElse">
<!--<![endif]-->