Rework standalone to use a synchronous loader that does not invoke Dart code

runtime/bin/dartutils.cc

Index: runtime/bin/dartutils.cc
diff --git a/runtime/bin/dartutils.cc b/runtime/bin/dartutils.cc
index b7f418b7a7cab7c68bbed5b6373039ae6fb55c26..49e32bea60cb9c1dee8cdd09ed1066e400b3ed3e 100644
--- a/runtime/bin/dartutils.cc
+++ b/runtime/bin/dartutils.cc
@@ -379,6 +379,17 @@ Dart_Handle DartUtils::ResolveUri(Dart_Handle library_url, Dart_Handle url) {
 }
 
 
+Dart_Handle DartUtils::ResolveScript(Dart_Handle url) {
+  const int kNumArgs = 1;
+  Dart_Handle dart_args[kNumArgs];
+  dart_args[0] = url;
+  return Dart_Invoke(DartUtils::BuiltinLib(),
+                     NewString("_resolveScriptUri"),
+                     kNumArgs,
+                     dart_args);
+}
+
+
 static Dart_Handle LoadDataAsync_Invoke(Dart_Handle tag,
                                         Dart_Handle url,
                                         Dart_Handle library_url) {
@@ -747,7 +758,7 @@ Dart_Handle DartUtils::SetupPackageRoot(const char* package_root,
     Dart_Handle dart_args[kNumArgs];
     dart_args[0] = result;
     result = Dart_Invoke(DartUtils::BuiltinLib(),
-                         NewString("_loadPackagesMap"),
+                         NewString("_setPackagesMap"),
                          kNumArgs,
                          dart_args);
     RETURN_IF_ERROR(result);