fix(ngc): work with typescript@next

This is required due to breaking change in TS, see
https://github.com/Microsoft/TypeScript/pull/8841#issuecomment-227300348

tools/@angular/tsc-wrapped/src/tsc.ts

@@ -54,9 +54,11 @@ export class Tsc implements CompilerInterface {
     this.basePath = basePath;
 
     // Allow a directory containing tsconfig.json as the project value
+    // Note, TS@next returns an empty array, while earlier versions throw
     try {
-      this.readDirectory(project);
-      project = path.join(project, 'tsconfig.json');
+      if (this.readDirectory(project).length > 0) {
+        project = path.join(project, 'tsconfig.json');
+      }
     } catch (e) {
       // Was not a directory, continue on assuming it's a file
     }