Bug 1367905 - Try to run GC/CC slices, including forgetSkippable, during idle time, tweaks to keep reftest memory usage lower, r=mccr8

--HG--
extra : rebase_source : 850e4f25ef1ac18b768dc50dc4fa9b77f0743080

dom/base/nsJSEnvironment.cpp

@@ -240,6 +240,10 @@ public:
   Create(CollectorRunnerCallback aCallback, uint32_t aDelay,
          int64_t aBudget, bool aRepeating, void* aData = nullptr)
   {
+    if (sShuttingDown) {
+      return nullptr;
+    }
+
     RefPtr<CollectorRunner> runner =
       new CollectorRunner(aCallback, aDelay, aBudget, aRepeating, aData);
     runner->Schedule(false); // Initial scheduling shouldn't use idle dispatch.
@@ -1921,7 +1925,10 @@ InterSliceGCRunnerFired(TimeStamp aDeadline, void* aData)
 {
   nsJSContext::KillInterSliceGCRunner();
   MOZ_ASSERT(sActiveIntersliceGCBudget > 0);
-  int64_t budget = sActiveIntersliceGCBudget;
+  // We use longer budgets when timer runs since that means
+  // there hasn't been idle time recently and we may have significant amount
+  // garbage to collect.
+  int64_t budget = sActiveIntersliceGCBudget * 2;
   if (!aDeadline.IsNull()) {
     budget = int64_t((aDeadline - TimeStamp::Now()).ToMilliseconds());
   }

layout/tools/reftest/reftest-content.js

@@ -41,7 +41,6 @@ var gTimeoutHook = null;
 var gFailureTimeout = null;
 var gFailureReason;
 var gAssertionCount = 0;
-var gTestCount = 0;
 
 var gDebug;
 var gVerbose = false;
@@ -143,11 +142,7 @@ function StartTestURI(type, uri, timeout)
     // The GC is only able to clean up compartments after the CC runs. Since
     // the JS ref tests disable the normal browser chrome and do not otherwise
     // create substatial DOM garbage, the CC tends not to run enough normally.
-    ++gTestCount;
-    if (gTestCount % 500 == 0) {
-        CU.forceGC();
-        CU.forceCC();
-    }
+    windowUtils().runNextCollectorTimer();
 
     // Reset gExplicitPendingPaintCount in case there was a timeout or
     // the count is out of sync for some other reason