Bug 1033472 - Gaia linter, gaia-build tests aren't using NODE_MODULES_GI...

...T_URL and so connect to Github ("make: *** [node_modules] Error 2") r=yurenju

This changes how the node_modules directory is generated. Indeed, we don't use
the temporary directory as a direct dependency now, because its name can change
and we don't need to run the new target if the name changes.