fix(tabs): fix dynamic height demo for tabs

This issue was introduced in d860274.
Because of the new `svg-asset-cache` script, we need to init the module ourself.
The tabs demo was always working, because the `asset cache` initialized the module (unintentional).

Fixes #6780

src/components/tabs/demoDynamicHeight/script.js

@@ -0,0 +1 @@
+angular.module('tabsDemoDynamicHeight', ['ngMaterial']);