Use directory function

Author: weswigham

src/compiler/moduleSpecifiers.ts

@@ -159,7 +159,7 @@ namespace ts.moduleSpecifiers {
         for (const path of paths) {
             const resolved = links.get(path)!;
             if (startsWith(target, resolved + "/")) {
-                const relative = getRelativePathFromFile(resolved + "/file.ts", target, getCanonicalFileName);
+                const relative = getRelativePathFromDirectory(resolved, target, getCanonicalFileName);
                 const option = resolvePath(path, relative);
                 if (!host.fileExists || host.fileExists(option)) {
                     if (!options) options = [];