Use the isDeclarationVisible in checker to determine if the declaration needs to be emitted

This would help in unifying logic of when to check if the type is visible

tests/baselines/reference/declFileExportAssignmentImportInternalModule.js

@@ -31,5 +31,21 @@ module.exports = m;
 
 
 //// [declFileExportAssignmentImportInternalModule.d.ts]
+declare module m3 {
+    module m2 {
+        interface connectModule {
+            (res: any, req: any, next: any): void;
+        }
+        interface connectExport {
+            use: (mod: connectModule) => connectExport;
+            listen: (port: number) => void;
+        }
+    }
+    var server: {
+        (): m2.connectExport;
+        test1: m2.connectModule;
+        test2(): m2.connectModule;
+    };
+}
 import m = m3;
 export = m;