Exploit sharing when comparing and copying groups in ComputedStyle.

third_party/WebKit/Source/build/scripts/template_expander.py

Index: third_party/WebKit/Source/build/scripts/template_expander.py
diff --git a/third_party/WebKit/Source/build/scripts/template_expander.py b/third_party/WebKit/Source/build/scripts/template_expander.py
index 2edb5abc9b17765dc218170a46f7ece746a5cfc4..f23d3de17376323d472c124e8e35ae84a9089a93 100644
--- a/third_party/WebKit/Source/build/scripts/template_expander.py
+++ b/third_party/WebKit/Source/build/scripts/template_expander.py
@@ -36,7 +36,7 @@ sys.path.insert(1, os.path.join(_current_dir, *([os.pardir] * 4)))
 import jinja2
 
 
-def apply_template(path_to_template, params, filters=None):
+def apply_template(path_to_template, params, filters=None, tests=None):
     dirname, basename = os.path.split(path_to_template)
     path_to_templates = os.path.join(_current_dir, 'templates')
     jinja_env = jinja2.Environment(
@@ -46,15 +46,17 @@ def apply_template(path_to_template, params, filters=None):
         trim_blocks=True)  # so don't need {%- -%} everywhere
     if filters:
         jinja_env.filters.update(filters)
+    if tests:
+        jinja_env.tests.update(tests)
     template = jinja_env.get_template(basename)
     return template.render(params)
 
 
-def use_jinja(template_file_name, filters=None):
+def use_jinja(template_file_name, filters=None, tests=None):
     def real_decorator(generator):
         def generator_internal(*args, **kwargs):
             parameters = generator(*args, **kwargs)
-            return apply_template(template_file_name, parameters, filters=filters)
+            return apply_template(template_file_name, parameters, filters=filters, tests=tests)
         generator_internal.func_name = generator.func_name
         return generator_internal
     return real_decorator