Bug 1111361 - Allow for lower latency GC on elm micro-benchmark; r=jonco

--HG--
extra : rebase_source : 205068401b975345f79610581cd08afb754bf870

js/src/gc/Marking.cpp

@@ -1741,6 +1741,12 @@ GCMarker::processMarkStackTop(SliceBudget &budget)
   scan_value_array:
     MOZ_ASSERT(vp <= end);
     while (vp != end) {
+        budget.step();
+        if (budget.isOverBudget()) {
+            pushValueArray(obj, vp, end);
+            return;
+        }
+
         const Value &v = *vp++;
         if (v.isString()) {
             markAndScanString(obj, v.toString());

js/src/jsgc.cpp

@@ -3190,7 +3190,7 @@ GCRuntime::maybeAllocTriggerZoneGC(Zone *zone, const AutoLockGC &lock)
         // The threshold has been surpassed, immediately trigger a GC,
         // which will be done non-incrementally.
         triggerZoneGC(zone, JS::gcreason::ALLOC_TRIGGER);
-    } else if (usedBytes >= igcThresholdBytes) {
+    } else if (usedBytes >= igcThresholdBytes && interFrameGC) {
         // Reduce the delay to the start of the next incremental slice.
         if (zone->gcDelayBytes < ArenaSize)
             zone->gcDelayBytes = 0;