This has been done for several reasons:
* for consistency with the way we already manage the WDT and the
profiler icons;
* it makes the Exception independent from the location of the assets
(and from the asset() function)
* this is the second step to make the WebProfiler useable outside the
full-stack framework
see dbcd171dd3
The goal is to make things more decoupled and more reusable across
different bundles.
There will be a PR for the distribution bundle too to simplify the code
based on this PR.
