fix(34934): Completions for private members appear in JavaScript files

src/services/completions.ts

@@ -1235,7 +1235,7 @@ namespace ts.Completions {
                 // each individual type has. This is because we're going to add all identifiers
                 // anyways. So we might as well elevate the members that were at least part
                 // of the individual types to a higher status since we know what they are.
-                symbols.push(...getPropertiesForCompletion(type, typeChecker));
+                symbols.push(...filter(getPropertiesForCompletion(type, typeChecker), s => typeChecker.isValidPropertyAccessForCompletions(propertyAccess, type, s)));
             }
             else {
                 for (const symbol of type.getApparentProperties()) {

tests/cases/fourslash/completionsPrivateProperties_Js.ts

@@ -0,0 +1,20 @@
+/// <reference path="fourslash.ts" />
+
+// @allowJs: true
+// @Filename: a.d.ts
+////declare namespace A {
+////    class Foo {
+////        constructor();
+////
+////        private m1(): void;
+////        protected m2(): void;
+////
+////        m3(): void;
+////    }
+////}
+
+// @filename: b.js
+////let foo = new A.Foo();
+////foo./**/
+
+verify.completions({ marker: [""], includes: ["m3"], excludes: ["m1", "m2"] });