Re-enable all the windows warnings except 4267

BUILD.gn

 # Copyright 2016 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("//testing/test.gni")
 import("pdfium.gni")
 
 config("pdfium_config") {
   cflags = []
@@ skipping 25 matching lines @@
     if (current_cpu == "x64") {
       defines += [ "_FX_CPU_=_FX_X64_" ]
       cflags += [ "-fPIC" ]
     } else if (current_cpu == "x86") {
       defines += [ "_FX_CPU_=_FX_X86_" ]
     }
   }
 
   if (is_win) {
     cflags += [
-      "/wd4005",
-      "/wd4018",
-      "/wd4146",
-      "/wd4333",
-      "/wd4345",
       "/wd4267",
-
-      # TODO(ochang): Investigate if this can be fixed properly.
-      "/wd4201",
-
-      # TODO(thestig): Fix all instances, remove this, pdfium:29
-      "/wd4245",
-      "/wd4310",
-      "/wd4389",
-      "/wd4701",
-      "/wd4702",
-      "/wd4706",
-      "/wd4800",
     ]
   }
 
   if (is_clang || is_posix) {
     # TODO(thestig): Fix all instances, remove this, pdfium:29
     cflags += [ "-Wno-sign-compare" ]
   }
 
   if (is_posix && !is_clang) {  # When GCC.
     cflags += [ "-Wno-error=strict-overflow" ]
@@ skipping 1596 matching lines @@
       "//v8:v8_libplatform",
     ]
     include_dirs += [
       "//v8",
       "//v8/include",
     ]
     configs += [ "//v8:external_startup_data" ]
   }
   configs += [ ":pdfium_config" ]
 }