This patch makes EXTRA_{PP_,}JS_MODULES similar in functionality to
TESTING_JS_MODULES: we indicate the path relative to
$(FINAL_TARGET)/modules with an appropriate hierarchy of paths.
Many moz.build files define things that could be defined in parent
moz.build files. Keeping the number of moz.build files low helps with
build times due to less I/O and fewer directories traversed.
This patch eliminates a lot of moz.build files by moving their content
into parent moz.build files.
--HG--
extra : rebase_source : 0cfdf2697d10532e5b03cd27fbaadb41f42b837c
extra : amend_source : 0119d4e4881217f105e0e4ba1dfa9c8f7295f3e9
extra : histedit_source : eb49e62c67af2005fdc08d9c9a07f56bee98d558%2C50951e960e450f9b0e48fc7e8ec369d8666a63b0
