in make/plugin/plugin2/npjp2/Makefile, there is:

# In the future(Firefox 3.x), once we ammend NPAPI for cookie/proxy service, we
# should no longer need to depend on Mozilla headers.
ifeq ($(PLATFORM), windows)
  ifeq ($(ARCH), amd64)
    MOZHDRDIRS := $(shell $(ECHO) $(subst \,/,$(MOZILLA_HEADERS_PATH))/mozilla_headers_18.amd64/*)
  else
    MOZHDRDIRS := $(shell $(ECHO) $(subst \,/,$(MOZILLA_HEADERS_PATH))/mozilla_headers_18.win32/*)
  endif
else
MOZHDRDIRS := $(shell $(ECHO) $(subst \,/,$(MOZILLA_HEADERS_PATH))/mozilla_headers_18/*)
endif

this should be clean up, and removed if not needed

code in MozPluginNatives and MozPluginExport need to be cleaned up accordingly too.

examples:
// Get the global service manager which is the entry point (backdoor) for
// various services such as getting proxy/cookie and setting cookie etc.
// In the foreseeable future (Firefox 3.x) we should ammend NPAPI to add
// these services so that we can completely get out of the dependencies
// to XPCOM plugin which is supposed to be used only by Mozilla internally.
nsISupports* sm = NULL;
if (MozNPN_GetValue(NULL, NPNVserviceManager, (void*) &sm) != NPERR_NO_ERROR || sm == NULL) {
return;
}
it's in JNIEXPORT void JNICALL
Java_sun_plugin2_main_server_MozillaPlugin_initServiceManager(JNIEnv *env,
jclass unused) {


make sense to try to run that code with recent FF (disable NPAPI code before it) - it could be failing anyways. should remove code that is no longer needed.