Remove requirement that mojo::Environment be instantiated.

mojo/public/cpp/environment/lib/logging_only_environment.cc

Index: mojo/public/cpp/environment/lib/logging_only_environment.cc
diff --git a/mojo/public/cpp/environment/lib/logging_only_environment.cc b/mojo/public/cpp/environment/lib/logging_only_environment.cc
index 42c33ff3f6489afd1e0ce88af40c361327dca402..38b15b8656addc47d5b05f8a8d427580919c073b 100644
--- a/mojo/public/cpp/environment/lib/logging_only_environment.cc
+++ b/mojo/public/cpp/environment/lib/logging_only_environment.cc
@@ -12,13 +12,6 @@
 
 namespace mojo {
 
-Environment::Environment() {}
-
-Environment::Environment(const MojoAsyncWaiter* default_async_waiter,
-                         const MojoLogger* default_logger) {}
-
-Environment::~Environment() {}
-
 // static
 const MojoLogger* Environment::GetDefaultLogger() {
   return &internal::kDefaultLogger;