[ts] Support private methods overloads (#13876)

* [parser] Allow private methods overloads when parsing TS

* Add transform tests

* Fix estree

* Fix flow

packages/babel-parser/src/plugins/typescript/index.js

@@ -2015,7 +2015,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       const bodilessType =
         type === "FunctionDeclaration"
           ? "TSDeclareFunction"
-          : type === "ClassMethod"
+          : type === "ClassMethod" || type === "ClassPrivateMethod"
           ? "TSDeclareMethod"
           : undefined;
       if (bodilessType && !this.match(tt.braceL) && this.isLineTerminator()) {
@@ -2755,6 +2755,17 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       super.pushClassPrivateMethod(classBody, method, isGenerator, isAsync);
     }
 
+    declareClassPrivateMethodInScope(
+      node: N.ClassPrivateMethod | N.EstreeMethodDefinition | N.TSDeclareMethod,
+      kind: number,
+    ) {
+      if (node.type === "TSDeclareMethod") return;
+      // This happens when using the "estree" plugin.
+      if (node.type === "MethodDefinition" && !node.value.body) return;
+
+      super.declareClassPrivateMethodInScope(node, kind);
+    }
+
     parseClassSuper(node: N.Class): void {
       super.parseClassSuper(node);
       if (node.superClass && this.isRelational("<")) {