Update WPT test expectations for --release builds

python/servo/testing_commands.py

@@ -242,6 +242,8 @@ class MachCommands(CommandBase):
 
         os.environ["hosts_file_path"] = hosts_file_path
 
+        kwargs["debug"] = not kwargs["release"]
+
         run_file = path.abspath(path.join("tests", "wpt", "run_wpt.py"))
         run_globals = {"__file__": run_file}
         execfile(run_file, run_globals)

tests/wpt/metadata/html/semantics/embedded-content/the-img-element/Image-constructor.html.ini

@@ -0,0 +1,5 @@
+[Image-constructor.html]
+  type: testharness
+  [Image and HTMLImageElement share a prototype]
+    expected:
+      if not debug: FAIL