Mojo C++ bindings: make the generator use STL/WTF string/vector/map by default.

mojo/common/BUILD.gn

Index: mojo/common/BUILD.gn
diff --git a/mojo/common/BUILD.gn b/mojo/common/BUILD.gn
index 2edfb6d5c83561251d0e9f0dedfdb8e4af7e0f9b..44c6d812f3db9dc81e6da2f936e85daccabe7648 100644
--- a/mojo/common/BUILD.gn
+++ b/mojo/common/BUILD.gn
@@ -17,6 +17,8 @@ mojom("common_custom_types") {
   sources = [
     "common_custom_types.mojom",
   ]
+
+  use_new_wrapper_types = false
 }
 
 # GYP version: mojo/mojo_base.gyp:mojo_common_lib
@@ -52,6 +54,8 @@ mojom("test_common_custom_types") {
   public_deps = [
     ":common_custom_types",
   ]
+
+  use_new_wrapper_types = false
 }
 
 # GYP version: mojo/mojo_base.gyp:mojo_common_unittests