Tweak public APIs and use them in patch_sdk, dart2js, and kernel-service

pkg/front_end/tool/perf.dart

Index: pkg/front_end/tool/perf.dart
diff --git a/pkg/front_end/tool/perf.dart b/pkg/front_end/tool/perf.dart
index d5bc9255b89fce189976f8753f367449782ff283..4a21aff76a9e6e1b403c0d0be5751449c92ad512 100644
--- a/pkg/front_end/tool/perf.dart
+++ b/pkg/front_end/tool/perf.dart
@@ -145,9 +145,8 @@ Future<Program> generateKernel(Uri entryUri,
 
 _kernelForProgramViaDartk(Uri source, CompilerOptions options) async {
   var loader = await _createLoader(options, entry: source);
-  if (options.compileSdk) {
-    options.additionalLibraries.forEach(loader.loadLibrary);
-  }
+
+  /// CODE REVIEW COMMENT: additionalLibraries was empty
   loader.loadProgram(source, compileSdk: options.compileSdk);
   _reportErrors(loader.errors, options.onError);
   return loader.program;
@@ -186,7 +185,6 @@ DartOptions _convertOptions(CompilerOptions options) {
       // sdk sources.
       sdkSummary: options.compileSdk ? null : _uriToPath(options.sdkSummary),
       packagePath: _uriToPath(options.packagesFileUri),
-      customUriMappings: options.uriOverride,
       declaredVariables: options.declaredVariables);
 }