IDL: Fix union type support in cross-component partial interfaces

If a partial interface in modules extends an interface in core and uses
any union types, the generated bindings/modules/v8/V8*Partial.cpp file
needs to include UnionTypesModules.h. This did not happen, since use of
union types was only tracked per main (non-partial) interface.

BUG=240176

Review URL: https://codereview.chromium.org/684653009

git-svn-id: svn://svn.chromium.org/blink/trunk@185136 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/bindings/scripts/compute_interfaces_info_individual.py

@@ -168,11 +168,10 @@ class InterfaceInfoCollector(object):
         self.union_types = set()
 
     def add_paths_to_partials_dict(self, partial_interface_name, full_path,
-                                   this_include_path=None):
+                                   include_paths):
         paths_dict = self.partial_interface_files[partial_interface_name]
         paths_dict['full_paths'].append(full_path)
-        if this_include_path:
-            paths_dict['include_paths'].append(this_include_path)
+        paths_dict['include_paths'].extend(include_paths)
 
     def collect_info(self, idl_filename):
         """Reads an idl file and collects information which is required by the
@@ -212,7 +211,14 @@ class InterfaceInfoCollector(object):
         if definition.is_partial:
             # We don't create interface_info for partial interfaces, but
             # adds paths to another dict.
-            self.add_paths_to_partials_dict(definition.name, full_path, this_include_path)
+            partial_include_paths = []
+            if this_include_path:
+                partial_include_paths.append(this_include_path)
+            if this_union_types:
+                component = idl_filename_to_component(idl_filename)
+                partial_include_paths.append(
+                    'bindings/%s/v8/UnionTypes%s.h' % (component, component.capitalize()))
+            self.add_paths_to_partials_dict(definition.name, full_path, partial_include_paths)
             return
 
         # 'implements' statements can be included in either the file for the