Enable precompiled headers for Blink on Windows.

third_party/WebKit/Source/modules/modules.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.
 
 # DON'T INCLUDE modules_idl_files.gni FROM HERE.
 #
 # This file is shared with all modules' BUILD files which shouldn't need access
 # to the huge and slow lists of sources. If sharing is necessary, make a
 # separate .gni.
 import("//third_party/WebKit/Source/config.gni")
@@ skipping 25 matching lines @@
     ]
     if (defined(invoker.deps)) {
       deps += invoker.deps
     }
 
     # Take everything else not handled above from the invoker.
     forward_variables_from(invoker, "*", [ "deps" ])
   }
 }
 set_defaults("blink_modules_sources") {
-  # This sets the default list of configs when the blink_core_sources target
+  # This sets the default list of configs when the blink_modules_sources target
   # is defined. The default_compiler_configs comes from BUILDCONFIG.gn and
   # is the list normally applied to static libraries and source sets.
   configs = default_compiler_configs
   configs += [
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     "//build/config/compiler:no_size_t_to_int_warning",
     "//third_party/WebKit/Source:config",
     "//third_party/WebKit/Source/modules:modules_implementation",
     "//third_party/WebKit/Source:non_test_config",
     "//third_party/WebKit/Source:inside_blink",
   ]
   if (remove_webcore_debug_symbols) {
     configs -= [ "//build/config/compiler:default_symbols" ]
     configs += [ "//build/config/compiler:no_symbols" ]
   }
 }