Bug 1529306 - Trigger GC timers before CC timers in nsJSContext::RunNextCollectorTimer. r=mccr8

This fixes frequent jsreftest OOMs on Win32 because we weren't triggering GC
frequently enough. Bug 1377131 changed the timer ordering in this code and might
have regressed this.

Differential Revision: https://phabricator.services.mozilla.com/D20664

--HG--
extra : moz-landing-system : lando

dom/base/nsJSEnvironment.cpp

@@ -1904,16 +1904,16 @@ void nsJSContext::RunNextCollectorTimer(JS::GCReason aReason,
     // anything if a GC is in progress.
     MOZ_ASSERT(!sCCLockedOut,
                "Don't check the CC timers if the CC is locked out.");
-  }
 
-  if (sCCRunner) {
-    sCCRunner->SetDeadline(aDeadline);
-    runnable = sCCRunner;
-  }
+    if (sCCRunner) {
+      sCCRunner->SetDeadline(aDeadline);
+      runnable = sCCRunner;
+    }
 
-  if (sICCRunner) {
-    sICCRunner->SetDeadline(aDeadline);
-    runnable = sICCRunner;
+    if (sICCRunner) {
+      sICCRunner->SetDeadline(aDeadline);
+      runnable = sICCRunner;
+    }
   }
 
   if (runnable) {