Refactor URI processing of native extensions directive #import("dart-ext:foo").

runtime/bin/main.cc

Index: runtime/bin/main.cc
diff --git a/runtime/bin/main.cc b/runtime/bin/main.cc
index e0bee3ad42379b58dc3fe2279b1c2f3c84ecf6b0..f6613c31f98fe75c7e941cfc7ae0a02c1d9deaa5 100644
--- a/runtime/bin/main.cc
+++ b/runtime/bin/main.cc
@@ -263,13 +263,8 @@ static Dart_Handle LibraryTagHandler(Dart_LibraryTag tag,
     Dart_Handle dart_args[2];
     dart_args[0] = library_url;
     dart_args[1] = url;
-    if (is_dart_extension_url) {
-      return Dart_Invoke(
-          builtin_lib, Dart_NewString("_resolveExtensionUri"), 2, dart_args);
-    } else {
-      return Dart_Invoke(
-          builtin_lib, Dart_NewString("_resolveUri"), 2, dart_args);
-    }
+    return Dart_Invoke(
+        builtin_lib, Dart_NewString("_resolveUri"), 2, dart_args);
   }
   if (is_dart_scheme_url) {
     ASSERT(tag == kImportTag);
@@ -285,11 +280,6 @@ static Dart_Handle LibraryTagHandler(Dart_LibraryTag tag,
     } else {
       return Dart_Error("Do not know how to load '%s'", url_string);
     }
-  } else if (is_dart_extension_url) {
-    if (tag != kImportTag) {
-      return Dart_Error("Dart extensions must use import: '%s'", url_string);
-    }
-    return Extensions::LoadExtension(url_string, library);
   } else {
     // Get the file path out of the url.
     Dart_Handle builtin_lib = Builtin::LoadLibrary(Builtin::kBuiltinLibrary);
@@ -302,6 +292,12 @@ static Dart_Handle LibraryTagHandler(Dart_LibraryTag tag,
     }
     Dart_StringToCString(file_path, &url_string);
   }
+  if (is_dart_extension_url) {
+    if (tag != kImportTag) {
+      return Dart_Error("Dart extensions must use import: '%s'", url_string);
+    }
+    return Extensions::LoadExtension(url_string, library);
+  }
   result = DartUtils::LoadSource(NULL,
                                  library,
                                  url,