Fix content_gl_tests not starting on Windows debug bots.

BUG=416565
TBR=jmadill@chromium.org

Review URL: https://codereview.chromium.org/592043006

Cr-Commit-Position: refs/heads/master@{#296065}

content/content_gl_tests.isolate

@@ -51,6 +51,6 @@
     }],
   ],
   'includes': [
-    '../third_party/icu/icu.isolate',
+    '../base/base.isolate',
   ],
 }