Revert of Disable all GPU tests on N5X bot temporarily.

content/test/gpu/generate_buildbot_json.py

Index: content/test/gpu/generate_buildbot_json.py
diff --git a/content/test/gpu/generate_buildbot_json.py b/content/test/gpu/generate_buildbot_json.py
index 1ae945bece0cb4bdc3ede97296a9101433056747..83259fcecd3e16dce81755381051b63abb994f16 100755
--- a/content/test/gpu/generate_buildbot_json.py
+++ b/content/test/gpu/generate_buildbot_json.py
@@ -1432,9 +1432,6 @@
   return True
 
 def should_run_on_tester(tester_name, tester_config, test_config, is_fyi):
-  # TODO(jmadill): Re-enable when n5x fixed. See http://crbug.com/672502.
-  if 'Nexus 5X' in tester_name:
-    return False
   # Check if this config is disabled on this tester
   if 'disabled_tester_configs' in test_config:
     for dtc in test_config['disabled_tester_configs']: