Servo relies on several external files in /resources/, and the loading of these resources is delegated to the embedder. In this repo, libsimpleservo compiles them in with include_bytes!(), while the other three (servoshell, gstplugin, and unit tests) try to read them from the filesystem at runtime.

Our current logic for searching for the resources directory tries to accommodate both local dev in this repo (../../resources relative to servo, or a further ancestor in the case of unit tests) and nightly builds (resources relative to servo, or Resources relative to a further ancestor in the case of macOS):

1. let path = the current executable path
2. canonicalise path, resolving any symlinks
3. let path = parent of path
4. try path/resources
5. try path/Resources
6. go to step 3

But this fails if target is symlinked to another filesystem, like I recently did to exclude it from my backups:

% ls -l target
lrwxrwxrwx 1 delan users 25 Sep 28 15:34 target -> /cuffs/build/servo/target

This patch adds (or replaces those with, for unit tests) a few steps as follows:

7. let path = the current directory
8. try path/resources
9. let path = parent of path
10. go to step 8

The new logic:

• allows servoshell and unit tests to be run with a symlinked target directory
• does not require any special environment variables, so you can run target/debug/servo in e.g. renderdoc
• does not affect the behaviour of our nightly releases

• ./mach build -d does not report any errors
• ./mach test-tidy does not report any errors
• These changes fix servoshell and unit tests crash if target directory is symlinked #30536

• There are tests for these changes OR
• These changes do not require tests because ___