Merge pull request #2473 from chinmaygarde/cond_direc

Conditional directives are a snapshotter option. Remove the same from the embedder VM and add the flag to the precomp snapshotter.

sky/build/SnapshotterInvoke

@@ -143,6 +143,7 @@ SnapshotProject() {
       --url_mapping=dart:ui,${ui_path}                                         \
       --url_mapping=dart:vmservice_sky,$vm_service_path                        \
       --no-checked                                                             \
+      --conditional_directives                                                 \
       $main_path
 
   if [[ $? -ne 0 ]]; then

sky/engine/core/script/dart_init.cc

@@ -86,10 +86,6 @@ static const char* kDartBackgroundCompilationArgs[] = {
   "--background_compilation",
 };
 
-static const char *kDartConditionalDirectivesArgs[] = {
-    "--conditional_directives",
-};
-
 static const char* kDartCheckedModeArgs[] = {
     "--enable_asserts",
     "--enable_type_checks",
@@ -336,8 +332,6 @@ void InitDartVM() {
     args.append(kDartMirrorsArgs, arraysize(kDartMirrorsArgs));
     args.append(kDartBackgroundCompilationArgs,
                 arraysize(kDartBackgroundCompilationArgs));
-    args.append(kDartConditionalDirectivesArgs,
-                arraysize(kDartConditionalDirectivesArgs));
   }
 
   if (enable_checked_mode)