gn: Remove unnecessary v8 defaults

chrome/test/base/js2gtest.gni

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import("//build_overrides/v8.gni")
+import("//v8/gni/v8.gni")
 import("//v8/snapshot_toolchain.gni")
 
 # Variables:
 #   test_type: One of 'webui', 'unit' or 'extension' indicating what
 #       environment the test runs under.
 #   sources: List of javascript test source files.
 #   deps_js: Javascript file with closure library dependencies.  Only needed
 #       if the test fixtures use closureModuleDeps.
 #   gen_include_files: List of javascript files used in GEN_INCLUDE calls
 #       in the tests and therefore considered input to the C++ generation step.
@@ skipping 112 matching lines @@
     if (defined(invoker.deps)) {
       deps += invoker.deps
     }
     if (defined(invoker.extra_js_files)) {
       data_deps = [
         ":$copy_target_name",
       ]
     }
   }
 }