Remove redundant variable declaration in pdf/basic_plugin_test.js.

Review-Url: https://codereview.chromium.org/2102883004
Cr-Commit-Position: refs/heads/master@{#402695}

chrome/test/data/pdf/basic_plugin_test.js

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-var scriptingAPI;
-
 /**
  * These tests require that the PDF plugin be available to run correctly.
  */