Disable all warnings when compiling NSS.

runtime/tools/gyp/nss_configurations.gypi

Index: runtime/tools/gyp/nss_configurations.gypi
diff --git a/runtime/tools/gyp/nss_configurations.gypi b/runtime/tools/gyp/nss_configurations.gypi
index ac3e6120000b9f7f9cd069167a6fa71e574e936e..e3776e036b0d2e24b76d8f60ca4d67e8b1e2c86d 100644
--- a/runtime/tools/gyp/nss_configurations.gypi
+++ b/runtime/tools/gyp/nss_configurations.gypi
@@ -19,14 +19,7 @@
   },
   'target_defaults': {
     'cflags': [
-      '-Wno-unused-variable',
-      '-Wno-unused-but-set-variable',
-      '-Wno-missing-field-initializers',
-      '-Wno-uninitialized',
-      '-Wno-sign-compare',
-      '-Wno-empty-body',
-      '-Wno-type-limits',
-      '-Wno-pointer-to-int-cast',
+      '-w',
       '-UHAVE_CVAR_BUILT_ON_SEM',
     ],
     # Removes these flags from the list cflags.
@@ -46,6 +39,9 @@
     'configurations': {
       'Dart_Base': {
         'xcode_settings': {
+          'WARNING_CFLAGS': [
+            '-w',
+          ],
           'WARNING_CFLAGS!': [
             '-Wall',
             '-Wextra',