1533190 - Implement environment variable substitution in ResolvePath

Status: RESOLVED DUPLICATE of bug 1533200

(Core :: JavaScript Engine, enhancement)

Description

[Steve Fink [:sfink] [:s:]]

For some tryserver debugging, I wanted to call dumpHeap() from within a jsreftest and have the heap dump uploaded as an artifact. But there's no facility to get environment variables from within a reftest, as far as I can tell.

I'm not 100% sure this patch is a good idea, but it does allow a simple

dumpHeap("$MOZ_UPLOAD_DIR/heap.txt");

to do what I want. (Well, I also have to disable the sandbox for this to work, but that's doable with the --env flag on a try push.)

(Note that the JS shell does have os.getenv(), but the shell functions are not part of the getJSTestingFunctions() stuff; they aren't compiled into the browser at all.)