IDL: Put generated union type containers in separate files

Source/bindings/scripts/v8_union.py

Index: Source/bindings/scripts/v8_union.py
diff --git a/Source/bindings/scripts/v8_union.py b/Source/bindings/scripts/v8_union.py
index 4ed138fac624837e7d9b30a32819fd6e9c5c1986..f6c96f4ef4b0368d6f24beff4853055381c0c7a2 100644
--- a/Source/bindings/scripts/v8_union.py
+++ b/Source/bindings/scripts/v8_union.py
@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import v8_types
 import v8_utilities
 
 
@@ -12,7 +13,7 @@ UNION_H_INCLUDES = frozenset([
     'platform/heap/Handle.h',
 ])
 
-UNION_CPP_INCLUDES_BLACKLIST = frozenset([
+UNION_HEADER_INCLUDES_BLACKLIST = frozenset([
     # This header defines static functions needed to implement event handler
     # attributes in interfaces that implement GlobalEventHandlers. They are not
     # needed or used by UnionTypes*.cpp, so including the header causes
@@ -23,44 +24,12 @@ UNION_CPP_INCLUDES_BLACKLIST = frozenset([
 ])
 
 
-cpp_includes = set()
-header_forward_decls = set()
-
-
-def union_context(union_types, interfaces_info):
-    cpp_includes.clear()
-    header_forward_decls.clear()
-
-    # For container classes we strip nullable wrappers. For example,
-    # both (A or B)? and (A? or B) will become AOrB. This should be OK
-    # because container classes can handle null and it seems that
-    # distinguishing (A or B)? and (A? or B) doesn't make sense.
-    container_cpp_types = set()
-    union_types_for_containers = set()
-    nullable_cpp_types = set()
-    for union_type in union_types:
-        cpp_type = union_type.cpp_type
-        if cpp_type not in container_cpp_types:
-            union_types_for_containers.add(union_type)
-            container_cpp_types.add(cpp_type)
-        if union_type.includes_nullable_type:
-            nullable_cpp_types.add(cpp_type)
-
-    union_types_for_containers = sorted(union_types_for_containers,
-                                        key=lambda union_type: union_type.cpp_type)
-    nullable_cpp_types = sorted(nullable_cpp_types)
-
-    return {
-        'containers': [container_context(union_type, interfaces_info)
-                       for union_type in union_types_for_containers],
-        'cpp_includes': sorted(cpp_includes - UNION_CPP_INCLUDES_BLACKLIST),
-        'header_forward_decls': sorted(header_forward_decls),
-        'header_includes': sorted(UNION_H_INCLUDES),
-        'nullable_cpp_types': nullable_cpp_types,
-    }
+header_includes = set()
 
 
 def container_context(union_type, interfaces_info):
+    header_includes.clear()
+    header_includes.update(UNION_H_INCLUDES)
     members = []
 
     # These variables refer to member contexts if the given union type has
@@ -111,13 +80,15 @@ def container_context(union_type, interfaces_info):
     if dictionary_type and nullable_members == 1:
         raise Exception('%s has a dictionary and a nullable member' % union_type.name)
 
+    cpp_class = union_type.cpp_type
     return {
         'array_buffer_type': array_buffer_type,
         'array_buffer_view_type': array_buffer_view_type,
         'array_or_sequence_type': array_or_sequence_type,
         'boolean_type': boolean_type,
-        'cpp_class': union_type.cpp_type,
+        'cpp_class': cpp_class,
         'dictionary_type': dictionary_type,
+        'header_includes': sorted(header_includes - UNION_HEADER_INCLUDES_BLACKLIST),
         'includes_nullable_type': union_type.includes_nullable_type,
         'interface_types': interface_types,
         'members': members,
@@ -125,15 +96,15 @@ def container_context(union_type, interfaces_info):
         'numeric_type': numeric_type,
         'string_type': string_type,
         'type_string': str(union_type),
+        'v8_class': v8_types.v8_type(cpp_class),
     }
 
 
 def member_context(member, interfaces_info):
-    cpp_includes.update(member.includes_for_type)
+    header_includes.update(member.includes_for_type)
     interface_info = interfaces_info.get(member.name, None)
     if interface_info:
-        cpp_includes.update(interface_info.get('dependencies_include_paths', []))
-        header_forward_decls.add(member.implemented_as)
+        header_includes.update(interface_info.get('dependencies_include_paths', []))
     if member.is_nullable:
         member = member.inner_type
     return {