chore: add @babel/plugin-proposal-class-properties

Author: lokshunhung

.babelrc

@@ -15,5 +15,6 @@
         "onlyRemoveTypeImports": true
       }
     ]
-  ]
+  ],
+  "plugins": ["@babel/plugin-proposal-class-properties"]
 }

package.json

@@ -39,6 +39,7 @@
   "devDependencies": {
     "@babel/cli": "^7.0.0",
     "@babel/core": "^7.0.0",
+    "@babel/plugin-proposal-class-properties": "^7.0.0",
     "@babel/preset-env": "^7.0.0",
     "@babel/preset-typescript": "^7.0.0",
     "@typescript-eslint/parser": "^4.6.0",

yarn.lock

@@ -374,7 +374,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@babel/plugin-proposal-class-properties@npm:^7.12.1":
+"@babel/plugin-proposal-class-properties@npm:^7.0.0, @babel/plugin-proposal-class-properties@npm:^7.12.1":
   version: 7.12.1
   resolution: "@babel/plugin-proposal-class-properties@npm:7.12.1"
   dependencies:
@@ -2596,6 +2596,7 @@ __metadata:
   dependencies:
     "@babel/cli": ^7.0.0
     "@babel/core": ^7.0.0
+    "@babel/plugin-proposal-class-properties": ^7.0.0
     "@babel/preset-env": ^7.0.0
     "@babel/preset-typescript": ^7.0.0
     "@typescript-eslint/parser": ^4.6.0