Bug 1640839 - Add some helpers for enums to calculate the size and use it in EnumeratedArray. r=glandium,jgilbert,media-playback-reviewers,padenot

Differential Revision: https://phabricator.services.mozilla.com/D201334

Author: petervanderbeken

dom/animation/EffectCompositor.h

@@ -245,7 +245,7 @@ class EffectCompositor {
   // indicate that the style rule on the element is out of date but without
   // posting a restyle to update it.
   EnumeratedArray<CascadeLevel, nsTHashMap<PseudoElementHashEntry, bool>,
-                  CascadeLevel(kCascadeLevelCount)>
+                  kCascadeLevelCount>
       mElementsToRestyle;
 
   bool mIsInPreTraverse = false;

dom/base/FlushType.h

@@ -40,7 +40,7 @@ enum class FlushType : uint8_t {
 
 // Flush type strings that will be displayed in the profiler
 // clang-format off
-const EnumeratedArray<FlushType, const char*, FlushType::Count>
+const EnumeratedArray<FlushType, const char*, size_t(FlushType::Count)>
     kFlushTypeNames = {
   "",
   "Event",