Fix the union property kind if the property is union of exported variable of module

Fixes #929

tests/cases/fourslash/completionEntryForPropertyFromUnionOfModuleType.ts

@@ -0,0 +1,13 @@
+///<reference path="fourslash.ts" />
+
+////module E {
+////    export var n = 1;
+////}
+////module F {
+////    export var n = 1;
+////}
+////var q: typeof E | typeof F;
+////var j = q./*1*/
+
+goTo.marker('1');
+verify.completionListContains('n', "(property) n: number");