Remove SPS profiler.

- Conditionals and code blocks. (MOZ_ENABLE_PROFILER_SPS)
- Stub out several profiler-only functions.

xpcom/build/XPCOMInit.cpp

@@ -1040,20 +1040,6 @@ ShutdownXPCOM(nsIServiceManager* aServMgr)
     NS_WARNING("Component Manager was never created ...");
   }
 
-#ifdef MOZ_ENABLE_PROFILER_SPS
-  // In optimized builds we don't do shutdown collections by default, so
-  // uncollected (garbage) objects may keep the nsXPConnect singleton alive,
-  // and its XPCJSContext along with it. However, we still destroy various
-  // bits of state in JS_ShutDown(), so we need to make sure the profiler
-  // can't access them when it shuts down. This call nulls out the
-  // JS pseudo-stack's internal reference to the main thread JSContext,
-  // duplicating the call in XPCJSContext::~XPCJSContext() in case that
-  // never fired.
-  if (PseudoStack* stack = mozilla_get_pseudo_stack()) {
-    stack->sampleContext(nullptr);
-  }
-#endif
-
   if (sInitializedJS) {
     // Shut down the JS engine.
     JS_ShutDown();