import changes from `dev' branch of rmottola/Arctic-Fox:

- Bug 1148070 - Change nsIClassInfo::getHelperForLanguage() to getScriptableHelper(). r=bholley (30d208d40)
- Bug 1147951, part 3 - Remove unnecessary includes of nsIProgrammingLanguage. r=baku (79a91c51b)
- Bug 1149807 - Remove some unused nsIProgrammingLanguage.h includes. r=froydnj (88a388df4)
- Bug 1147572 - Remove implementation language field from DOM class info. r=jst (3491499e0)
- Bug 1150197 - Remove useless null checks after allocating memory with new from xpcom/threads/; r=froydnj (8e8357735)

xpcom/threads/nsTimerImpl.cpp

@@ -304,9 +304,6 @@ nsTimerImpl::Startup()
   nsTimerEvent::Init();
 
   gThread = new TimerThread();
-  if (!gThread) {
-    return NS_ERROR_OUT_OF_MEMORY;
-  }
 
   NS_ADDREF(gThread);
   rv = gThread->InitLocks();
@@ -829,9 +826,6 @@ NS_NewTimer(nsITimer** aResult, nsTimerCallbackFunc aCallback, void* aClosure,
             uint32_t aDelay, uint32_t aType)
 {
   nsTimerImpl* timer = new nsTimerImpl();
-  if (!timer) {
-    return NS_ERROR_OUT_OF_MEMORY;
-  }
   NS_ADDREF(timer);
 
   nsresult rv = timer->InitWithFuncCallback(aCallback, aClosure,