Add constants and primitive type readonly attributes to Python IDL compiler

Source/bindings/templates/attributes.cpp

+{% macro attribute_getter(attribute) %}
+static void {{attribute.name}}AttributeGetter(v8::Local<v8::String> name, const v8::PropertyCallbackInfo<v8::Value>& info)
+{
+    {{cpp_class_name}}* imp = {{v8_class_name}}::toNative(info.Holder());
+{% if attribute.should_keep_attribute_alive %}
+    {{attribute.cpp_type}} result = imp->{{attribute.cpp_method_name}}();
+    if (result.get() && DOMDataStore::setReturnValueFromWrapper<{{attribute.v8_type}}>(info.GetReturnValue(), result.get()))
+        return;
+    v8::Handle<v8::Value> wrapper = toV8(result.get(), info.Holder(), info.GetIsolate());
+    if (!wrapper.IsEmpty()) {
+        V8HiddenPropertyName::setNamedHiddenReference(info.Holder(), "{{attribute.name}}", wrapper);
+        v8SetReturnValue(info, wrapper);
+    }
+{% else %}
+    {{attribute.return_v8_value_statement | indent}}
+{% endif %}
+    return;
+}
+{% endmacro %}
+
+
+{##############################################################################}
+{% macro attribute_getter_callback(attribute) %}
+static void {{attribute.name}}AttributeGetterCallback(v8::Local<v8::String> name, const v8::PropertyCallbackInfo<v8::Value>& info)
+{
+    TRACE_EVENT_SET_SAMPLING_STATE("Blink", "DOMGetter");
+    {{cpp_class_name}}V8Internal::{{attribute.name}}AttributeGetter(name, info);
+    TRACE_EVENT_SET_SAMPLING_STATE("V8", "Execution");
+}
+{% endmacro %}
+
+
+{##############################################################################}
+{% macro class_attributes() %}

[haraken, 2013/08/26 09:33:40]

Where is install_attributes() or something like that? It looks inconsistent that
we have install_consts() in constants.cpp but don't have install_attributes() in
attributes.cpp.

Also, I might want to remove class_attributes() by moving the contents to
install_attributes(). See my comment in constants.cpp.

[Nils Barth (inactive), 2013/08/27 02:59:27]

V8DOMConfiguration::installAttributes is only called once, on Window (Perl line
4189).
V8DOMConfiguration::installAttribute is called for RuntimeEnabled attributes,
which we haven't ported to Python yet.
It's in the WIP, but not in this CL:
https://codereview.chromium.org/17572008/diff/181001/Source/bindings/template...
Got it (see comments below).
It involves a bit of messing reordering of the Perl CG, so I'll do in a
follow-up.

+static const V8DOMConfiguration::AttributeConfiguration {{v8_class_name}}Attributes[] = {
+{% for attribute in attributes %}
+    {"{{attribute.name}}", {{cpp_class_name}}V8Internal::{{attribute.name}}AttributeGetterCallback, 0, 0, 0, 0, static_cast<v8::AccessControl>(v8::DEFAULT), static_cast<v8::PropertyAttribute>(v8::None), 0 /* on instance */},
+{% endfor %}
+};
+{% endmacro %}