Restructure code to enable reloading when a kernel dill file is specified on the command line inste…

runtime/bin/loader.cc

Index: runtime/bin/loader.cc
diff --git a/runtime/bin/loader.cc b/runtime/bin/loader.cc
index 62a655dc35aa72ade12e4d28c79d916eda4a74b8..b25f3c86f6fd5e2718cfba066d7cfd6f09a8abeb 100644
--- a/runtime/bin/loader.cc
+++ b/runtime/bin/loader.cc
@@ -650,25 +650,26 @@ Dart_Handle Loader::LibraryTagHandler(Dart_LibraryTag tag,
     }
     return Dart_DefaultCanonicalizeUrl(library_url, url);
   }
-  if (dfe.UseDartFrontend()) {
-    Dart_Isolate current = Dart_CurrentIsolate();
-    if (!Dart_IsServiceIsolate(current) && !Dart_IsKernelIsolate(current)) {
-      // When using DFE the library tag handler should be called only when we
-      // are reloading scripts.
-      ASSERT(tag == Dart_kScriptTag);
-      return dfe.ReloadScript(current, url);
-    }
-    // TODO(asiva) We need to ensure that the kernel and service isolates
-    // are always loaded from a kernel IR and do not use this path.
-  }
   const char* url_string = NULL;
   Dart_Handle result = Dart_StringToCString(url, &url_string);
   if (Dart_IsError(result)) {
     return result;
   }
-
-  // Special case for handling dart: imports and parts.
-  if (tag != Dart_kScriptTag) {
+  if (tag == Dart_kScriptTag) {
+    if (dfe.UseDartFrontend()) {
+      Dart_Isolate current = Dart_CurrentIsolate();
+      // Check if we are trying to reload a kernel file or if the '--dfe'
+      // option was specified and we need to compile sources using DFE.
+      if (!Dart_IsServiceIsolate(current) && !Dart_IsKernelIsolate(current)) {
+        // When using DFE the library tag handler should be called only when
+        // we are reloading scripts.
+        return dfe.ReloadScript(current, url_string);
+      }
+    }
+    // TODO(asiva) We need to ensure that the kernel and service isolates
+    // are always loaded from a kernel IR and do not use this path.
+  } else {
+    // Special case for handling dart: imports and parts.
     // Grab the library's url.
     Dart_Handle library_url = Dart_LibraryUrl(library);
     if (Dart_IsError(library_url)) {