bindings: Supports per-member [Exposed] for attributes on prototype.

Source/bindings/scripts/v8_interface.py

Index: Source/bindings/scripts/v8_interface.py
diff --git a/Source/bindings/scripts/v8_interface.py b/Source/bindings/scripts/v8_interface.py
index 0ecfb2b32ad236a47cb9071aadb403ab980f247e..8c4aef85f6e69b9532bd6c8327f01e167c545e18 100644
--- a/Source/bindings/scripts/v8_interface.py
+++ b/Source/bindings/scripts/v8_interface.py
@@ -298,7 +298,6 @@ def interface_context(interface):
                   attribute['runtime_enabled_function'])
              and attribute['should_be_exposed_to_script']
              for attribute in attributes),
-        'has_conditional_attributes': has_conditional_attributes,
         'has_constructor_attributes': any(attribute['constructor_type'] for attribute in attributes),
         'has_replaceable_attributes': any(attribute['is_replaceable'] for attribute in attributes),
     })
@@ -560,6 +559,20 @@ def interface_context(interface):
         'methods': methods,
     })
 
+    # Conditionally enabled members
+    has_conditional_attributes_on_instance = any(
+        attribute['exposed_test'] and attribute['on_instance']
+        for attribute in attributes)
+    has_conditional_attributes_on_prototype = any(
+        attribute['exposed_test'] and attribute['on_prototype']
+        for attribute in attributes)
+    context.update({
+        'has_conditional_attributes_on_instance':
+            has_conditional_attributes_on_instance,
+        'has_conditional_attributes_on_prototype':
+            has_conditional_attributes_on_prototype,
+    })
+
     context.update({
         'indexed_property_getter': property_getter(interface.indexed_property_getter, ['index']),
         'indexed_property_setter': property_setter(interface.indexed_property_setter, interface),