Fix issue 8094:

runtime/bin/dartutils.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "bin/dartutils.h"
 
 #include "bin/extensions.h"
 #include "bin/directory.h"
 #include "bin/file.h"
 #include "bin/io_buffer.h"
@@ skipping 288 matching lines @@
     // Resolve the url within the context of the library's URL.
     Dart_Handle builtin_lib =
         Builtin::LoadAndCheckLibrary(Builtin::kBuiltinLibrary);
     Dart_Handle library_url = Dart_LibraryUrl(library);
     if (Dart_IsError(library_url)) {
       return library_url;
     }
     return ResolveUri(library_url, url, builtin_lib);
   }
   if (is_dart_scheme_url) {
-    ASSERT(tag == kImportTag);
-    // Handle imports of other built-in libraries present in the SDK.
-    Builtin::BuiltinLibraryId id;
-    if (DartUtils::IsDartCryptoLibURL(url_string)) {
-      id = Builtin::kCryptoLibrary;
-    } else if (DartUtils::IsDartIOLibURL(url_string)) {
-      id = Builtin::kIOLibrary;
-    } else if (DartUtils::IsDartJsonLibURL(url_string)) {
-      id = Builtin::kJsonLibrary;
-    } else if (DartUtils::IsDartUriLibURL(url_string)) {
-      id = Builtin::kUriLibrary;
-    } else if (DartUtils::IsDartUtfLibURL(url_string)) {
-      id = Builtin::kUtfLibrary;
+    if (tag == kImportTag) {
+      // Handle imports of other built-in libraries present in the SDK.
+      Builtin::BuiltinLibraryId id;
+      if (DartUtils::IsDartCryptoLibURL(url_string)) {
+        id = Builtin::kCryptoLibrary;
+      } else if (DartUtils::IsDartIOLibURL(url_string)) {
+        id = Builtin::kIOLibrary;
+      } else if (DartUtils::IsDartJsonLibURL(url_string)) {
+        id = Builtin::kJsonLibrary;
+      } else if (DartUtils::IsDartUriLibURL(url_string)) {
+        id = Builtin::kUriLibrary;
+      } else if (DartUtils::IsDartUtfLibURL(url_string)) {
+        id = Builtin::kUtfLibrary;
+      } else {
+        return Dart_Error("Do not know how to load '%s'", url_string);
+      }
+      return Builtin::LoadAndCheckLibrary(id);
     } else {
-      return Dart_Error("Do not know how to load '%s'", url_string);
+      ASSERT(tag == kSourceTag);
+      return Dart_Error("Unable to load source '%s' ", url_string);
     }
-    return Builtin::LoadAndCheckLibrary(id);
   } else {
     // Get the file path out of the url.
     Dart_Handle builtin_lib =
         Builtin::LoadAndCheckLibrary(Builtin::kBuiltinLibrary);
     Dart_Handle file_path = FilePathFromUri(url, builtin_lib);
     if (Dart_IsError(file_path)) {
       return file_path;
     }
     Dart_StringToCString(file_path, &url_string);
   }
@@ skipping 377 matching lines @@
 
 CObject* CObject::NewOSError(OSError* os_error) {
   CObject* error_message =
       new CObjectString(CObject::NewString(os_error->message()));
   CObjectArray* result = new CObjectArray(CObject::NewArray(3));
   result->SetAt(0, new CObjectInt32(CObject::NewInt32(kOSError)));
   result->SetAt(1, new CObjectInt32(CObject::NewInt32(os_error->code())));
   result->SetAt(2, error_message);
   return result;
 }