[bindings] Implement an ExperimentEnabled IDL extended attribute.

third_party/WebKit/Source/bindings/scripts/v8_attributes.py

Index: third_party/WebKit/Source/bindings/scripts/v8_attributes.py
diff --git a/third_party/WebKit/Source/bindings/scripts/v8_attributes.py b/third_party/WebKit/Source/bindings/scripts/v8_attributes.py
index 6535851e61147d90645e281a66d205d8ea6f9f08..5cb1c1f037761971ebc1b7bb2ebd425fc2ee2dae 100644
--- a/third_party/WebKit/Source/bindings/scripts/v8_attributes.py
+++ b/third_party/WebKit/Source/bindings/scripts/v8_attributes.py
@@ -50,7 +50,7 @@ def attribute_context(interface, attribute):
     extended_attributes = attribute.extended_attributes
 
     idl_type.add_includes_for_type(extended_attributes)
-    if idl_type.enum_values:
+    if idl_type.enum_values or v8_utilities.api_experiment_name(attribute):
         includes.add('core/inspector/ConsoleMessage.h')
 
     # [CheckSecurity]
@@ -109,6 +109,7 @@ def attribute_context(interface, attribute):
         'deprecate_as': v8_utilities.deprecate_as(attribute),  # [DeprecateAs]
         'enum_type': idl_type.enum_type,
         'enum_values': idl_type.enum_values,
+        'api_experiment_name': v8_utilities.api_experiment_name(attribute),  # [APIExperimentEnabled]
         'exposed_test': v8_utilities.exposed(attribute, interface),  # [Exposed]
         'has_custom_getter': has_custom_getter(attribute),
         'has_custom_setter': has_custom_setter(attribute),
@@ -505,7 +506,7 @@ def is_constructor_attribute(attribute):
 
 
 def update_constructor_attribute_context(interface, attribute, context):
-    context['needs_constructor_getter_callback'] = context['measure_as'] or context['deprecate_as']
+    context['needs_constructor_getter_callback'] = context['measure_as'] or context['deprecate_as'] or context['api_experiment_name']
     # When the attribute name is the same as the interface name, do not generate
     # callback functions for each attribute and use
     # {{cpp_class}}ConstructorAttributeSetterCallback.  Otherwise, generate