add new test for getReferences on enums

tests/cases/fourslash/referencesForEnums.ts

@@ -0,0 +1,22 @@
+/// <reference path='fourslash.ts'/>
+
+////enum E {
+////    /*value1*/value1 = 1,
+////    "value2" = value1,
+////    111 = 11
+////}
+////
+////E.value1;
+////E["value2"];
+////E./*value2*/value2;
+////E[/*value3*/111];
+
+
+goTo.marker("value1");
+verify.referencesCountIs(3);
+
+goTo.marker("value2");
+verify.referencesCountIs(3);
+
+goTo.marker("value3");
+verify.referencesCountIs(2);