Use non-pinned IDL for Dartium code gen

lib/dom/scripts/fremontcutbuilder.py

Index: lib/dom/scripts/fremontcutbuilder.py
diff --git a/lib/dom/scripts/fremontcutbuilder.py b/lib/dom/scripts/fremontcutbuilder.py
index e6079cefc35d2b728914c8c6365984bb64b0494d..5fe0722c65b3c9effe8894843cc442bdbb50675e 100755
--- a/lib/dom/scripts/fremontcutbuilder.py
+++ b/lib/dom/scripts/fremontcutbuilder.py
@@ -149,14 +149,14 @@ def main():
       ('IDBDatabase', 'transaction', 'mode'),
       ]
 
-  # Assume standard Dart checkout.
-  webcore_path = os.path.join(current_dir, '..', '..', '..',
-                              'third_party', 'WebCore')
+  # Assume Dartium checkout.
+  webcore_path = os.path.join(current_dir, '..', '..', '..', '..',
+                              'third_party', 'WebKit', 'Source', 'WebCore')
 
   if not os.path.exists(webcore_path):
-    # Dartium checkout.
-    webcore_path = os.path.join(current_dir, '..', '..', '..', '..',
-                                'third_party', 'WebKit', 'Source', 'WebCore')
+    # Fall back to standard Dart checkout.
+    webcore_path = os.path.join(current_dir, '..', '..', '..',
+                                'third_party', 'WebCore')
 
   for dir_name in webkit_dirs:
     dir_path = os.path.join(webcore_path, dir_name)