Revert "Support 'dart.library.X' env variables in the VM."

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
diff --git a/runtime/vm/dart_api_impl.cc b/runtime/vm/dart_api_impl.cc
index ac2b4613d296d8ed8a45b87bacbda6537a879d94..a3bccb69463c5abb9e4dc11217e3eefc7207d548 100644
--- a/runtime/vm/dart_api_impl.cc
+++ b/runtime/vm/dart_api_impl.cc
@@ -4949,35 +4949,6 @@ DART_EXPORT void Dart_SetWeakHandleReturnValue(Dart_NativeArguments args,
 
 
 // --- Environment ---
-RawString* Api::GetEnvironmentValue(Thread* thread, const String& name) {
-  String& result = String::Handle(CallEnvironmentCallback(thread, name));
-  if (result.IsNull()) {
-    // Every 'dart:X' library introduces an environment variable
-    // 'dart.library.X' that is set to 'true'.
-    const String& prefix = Symbols::DartLibrary();
-    if (name.StartsWith(prefix)) {
-      const String& library_name =
-          String::Handle(String::SubString(name, prefix.Length()));
-      if (!library_name.IsNull()) {
-        const String& dart_library_name =
-            String::Handle(String::Concat(Symbols::DartScheme(), library_name));
-        const Library& library =
-            Library::Handle(Library::LookupLibrary(dart_library_name));
-        if (!library.IsNull()) {
-          return Symbols::True().raw();
-        }
-      }
-    }
-    // Check for default VM provided values. If it was not overriden on the
-    // command line.
-    if (Symbols::DartIsVM().Equals(name)) {
-      return Symbols::True().raw();
-    }
-  }
-  return result.raw();
-}
-
-
 RawString* Api::CallEnvironmentCallback(Thread* thread, const String& name) {
   Isolate* isolate = thread->isolate();
   Dart_EnvironmentCallback callback = isolate->environment_callback();
@@ -4999,6 +4970,15 @@ RawString* Api::CallEnvironmentCallback(Thread* thread, const String& name) {
           String::Handle(String::New("Illegal environment value")));
     }
   }
+  if (result.IsNull()) {
+    // TODO(iposva): Determine whether builtin values can be overriden by the
+    // embedder.
+    // Check for default VM provided values. If it was not overriden on the
+    // command line.
+    if (Symbols::DartIsVM().Equals(name)) {
+      return Symbols::True().raw();
+    }
+  }
   return result.raw();
 }