Fix regression while I worked on removing support for isolate_dependency_tracked.

content/content_unittests.isolate

 # Copyright (c) 2013 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.
 {
   'conditions': [
     ['OS=="android" or OS=="linux" or OS=="mac" or OS=="win"', {
       'variables': {
         'files': [
           '../media/test/data/',
           'test/data/',
@@ skipping 42 matching lines @@
     }],
     ['OS=="linux" and use_ozone==0', {
       'variables': {
         'files': [
           '<(PRODUCT_DIR)/xdisplaycheck<(EXECUTABLE_SUFFIX)',
         ],
       },
     }],
     ['OS=="linux" and libpeer_target_type=="loadable_module"', {
       'variables': {
-        'isolate_dependency_tracked': [
+        'files': [
           '<(PRODUCT_DIR)/lib/libpeerconnection.so',
         ],
       },
     }],
     ['OS=="mac"', {
       'variables': {
         'command': [
           '../testing/test_env.py',
           '<(PRODUCT_DIR)/content_unittests<(EXECUTABLE_SUFFIX)',
           '--brave-new-test-launcher',
@@ skipping 25 matching lines @@
     }],
     ['OS=="win" and (fastbuild==0 or fastbuild==1)', {
       'variables': {
         'files': [
           '<(PRODUCT_DIR)/content_unittests.exe.pdb',
         ],
       },
     }],
     ['OS=="win" and libpeer_target_type=="loadable_module"', {
       'variables': {
-        'isolate_dependency_tracked': [
+        'files': [
           '<(PRODUCT_DIR)/libpeerconnection.dll',
         ],
       },
     }],
   ],
   'includes': [
     '../base/base.isolate',
   ],
 }