Bug 960749 - Improve error messages when < and > are used in filenames. r=bsmedberg, a=1.4+

* Unify OS_FILE_ILLEGAL_CHARACTERS
* Provide KNOWN_PATH_SEPARATORS in addition to FILE_PATH_SEPARATOR.
* Update nsExternalAppHandler to use KNOWN_PATH_SEPARATORS instead of
  FILE_PATH_SEPARATOR when removing path separators.
* Fix DownloadsIPC.jsm when compiling with MOZ_DEBUG (would throw on undefined download.id).
* Add test for stripping out illegal characters when downloading.
Bug 986253 - Limit a number of Fence to 4 per message. r=nical, a=1.4+
Bug 984673 - Do not compress PBrowser::UpdateFrame. r=kats, a=1.4+
Bug 949537 - Setup substring matching for Chilean numbers. r=gwagner, a=1.4+