Remove var in Libraries/emitter/* (#22087)

Summary:
Replaces the keywords var with const in Libraries/emitter/EventValidator.js

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- [x] Check npm run flow
- [x] Check npm run flow-check-ios
- [x] Check npm run flow-check-android

[GENERAL] [ENHANCEMENT] [Libraries/emitter] - remove `var`
Pull Request resolved: #22087

Differential Revision: D12918444

Pulled By: TheSavior

fbshipit-source-id: 630ccb283fd6c3118a22124a656038eac4a88599

Libraries/vendor/emitter/EventValidator.js

@@ -71,21 +71,21 @@ if (__DEV__) {
     }
   };
 
-  var closestTypeFor = function(type, allowedTypes) {
+  const closestTypeFor = function(type, allowedTypes) {
     const typeRecommendations = allowedTypes.map(
       typeRecommendationFor.bind(this, type),
     );
     return typeRecommendations.sort(recommendationSort)[0];
   };
 
-  var typeRecommendationFor = function(type, recommendedType) {
+  const typeRecommendationFor = function(type, recommendedType) {
     return {
       type: recommendedType,
       distance: damerauLevenshteinDistance(type, recommendedType),
     };
   };
 
-  var recommendationSort = function(recommendationA, recommendationB) {
+  const recommendationSort = function(recommendationA, recommendationB) {
     if (recommendationA.distance < recommendationB.distance) {
       return -1;
     } else if (recommendationA.distance > recommendationB.distance) {
@@ -95,11 +95,11 @@ if (__DEV__) {
     }
   };
 
-  var isCloseEnough = function(closestType, actualType) {
+  const isCloseEnough = function(closestType, actualType) {
     return closestType.distance / actualType.length < 0.334;
   };
 
-  var damerauLevenshteinDistance = function(a, b) {
+  const damerauLevenshteinDistance = function(a, b) {
     let i, j;
     const d = [];