gn: add Blink GC plugin options

third_party/WebKit/Source/config.gni

 # Copyright 2014 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/config/ui.gni")
 import("//third_party/WebKit/public/features.gni")
 
 if (is_android) {
   import("//build/config/android/config.gni")
 }
 if (current_cpu == "arm") {
   import("//build/config/arm.gni")
 }
 
 declare_args() {
-  # Set to true to enable the clang plugin that checks the usage of the Blink
-  # garbage-collection infrastructure during compilation.
-  blink_gc_plugin = true
-
   # If true, doesn't compile debug symbols into webcore reducing the
   # size of the binary and increasing the speed of gdb.
   remove_webcore_debug_symbols = false
 
   # If true, enables blink logging macros (WTF_LOG and friends) unconditionally.
   # When false, blink logging macros are enabled only if assertions are enabled.
   blink_logging_always_on = false
 
   # If true, defaults image interpolation to low quality.
   use_low_quality_image_interpolation = is_android
@@ skipping 56 matching lines @@
 }
 
 # feature_defines_string -------------------------------------------------------
 
 # Convert the list to a space-separated string for passing to scripts.
 # This would be the equivalent of passing '<(feature_defines)' in GYP.
 feature_defines_string =
     exec_script("build/gn_list_to_space_separated_string.py",
                 feature_defines_list,
                 "trim string")