Bug 1790336 - Part 2: Increase balanced heap growth factor r=sfink

Increasing this parameter gives us parity on our benchmarks in the testing I've
done so far.

Differential Revision: https://phabricator.services.mozilla.com/D157095

js/src/gc/Scheduling.h

@@ -387,7 +387,7 @@ static const double HighFrequencyLargeHeapGrowth = 1.5;
 static const double LowFrequencyHeapGrowth = 1.5;
 
 /* JSGC_HEAP_GROWTH_FACTOR */
-static const double HeapGrowthFactor = 40.0;
+static const double HeapGrowthFactor = 50.0;
 
 /* JSGC_MIN_EMPTY_CHUNK_COUNT */
 static const uint32_t MinEmptyChunkCount = 1;

modules/libpref/init/all.js

@@ -1044,7 +1044,7 @@ pref("javascript.options.mem.gc_low_frequency_heap_growth", 150);
 pref("javascript.options.mem.gc_balanced_heap_limits", false);
 
 // JSGC_HEAP_GROWTH_FACTOR
-pref("javascript.options.mem.gc_heap_growth_factor", 40);
+pref("javascript.options.mem.gc_heap_growth_factor", 50);
 
 // JSGC_ALLOCATION_THRESHOLD
 pref("javascript.options.mem.gc_allocation_threshold_mb", 27);