IDL: Merge duplicating local variable assignment in attribute_getter

Source/bindings/templates/attributes.cpp

 {##############################################################################}
 {% macro attribute_getter(attribute, world_suffix) %}
 {% filter conditional(attribute.conditional_string) %}
 static void {{attribute.name}}AttributeGetter{{world_suffix}}(
 {%- if attribute.is_expose_js_accessors %}
 const v8::FunctionCallbackInfo<v8::Value>& info
 {%- else %}
 const v8::PropertyCallbackInfo<v8::Value>& info
 {%- endif %})
 {
@@ skipping 30 matching lines @@
     {% if attribute.is_call_with_script_state %}
     ScriptState* scriptState = ScriptState::current(info.GetIsolate());
     {% endif %}
     {% if attribute.is_check_security_for_node or
           attribute.is_getter_raises_exception %}
     ExceptionState exceptionState(ExceptionState::GetterContext, "{{attribute.name}}", "{{interface_name}}", holder, info.GetIsolate());
     {% endif %}
     {% if attribute.is_nullable and not attribute.has_type_checking_nullable %}
     bool isNull = false;
     {% endif %}
-    {# FIXME: consider always using a local variable for value #}
-    {% if attribute.cached_attribute_validation_method or
-          attribute.is_getter_raises_exception or
-          attribute.is_nullable or
-          attribute.reflect_only or
-          attribute.idl_type == 'EventHandler' %}
-    {{attribute.cpp_type}} {{attribute.cpp_value}} = {{attribute.cpp_value_original}};
+    {% if attribute.cpp_value_original %}
+    {{attribute.cpp_type}} {{attribute.cpp_value}}({{attribute.cpp_value_original}});
     {% endif %}
     {# Checks #}
     {% if attribute.is_getter_raises_exception %}
     if (UNLIKELY(exceptionState.throwIfNeeded()))
         return;
     {% endif %}
     {% if attribute.is_check_security_for_node %}
     {# FIXME: use a local variable to not call getter twice #}
     if (!BindingSecurity::shouldAllowAccessToNode(info.GetIsolate(), {{attribute.cpp_value}}, exceptionState)) {
         v8SetReturnValueNull(info);
@@ skipping 14 matching lines @@
     {% endif %}
         v8SetReturnValueNull(info);
         return;
     }
     {% endif %}
     {% if attribute.cached_attribute_validation_method %}
     V8HiddenValue::setHiddenValue(info.GetIsolate(), holder, propertyName, {{attribute.cpp_value_to_v8_value}});
     {% endif %}
     {# v8SetReturnValue #}
     {% if attribute.is_keep_alive_for_gc %}
-    {# FIXME: merge local variable assignment with above #}
-    {{attribute.cpp_type}} result({{attribute.cpp_value}});
-    if (result && DOMDataStore::setReturnValueFromWrapper{{world_suffix}}<{{attribute.v8_type}}>(info.GetReturnValue(), result.get()))
+    if ({{attribute.cpp_value}} && DOMDataStore::setReturnValueFromWrapper{{world_suffix}}<{{attribute.v8_type}}>(info.GetReturnValue(), {{attribute.cpp_value}}.get()))
         return;
-    v8::Handle<v8::Value> wrapper = toV8(result.get(), holder, info.GetIsolate());
+    v8::Handle<v8::Value> wrapper = toV8({{attribute.cpp_value}}.get(), holder, info.GetIsolate());
     if (!wrapper.IsEmpty()) {
         V8HiddenValue::setHiddenValue(info.GetIsolate(), holder, v8AtomicString(info.GetIsolate(), "{{attribute.name}}"), wrapper);
         {{attribute.v8_set_return_value}};
     }
     {% elif world_suffix %}
     {{attribute.v8_set_return_value_for_main_world}};
     {% else %}
     {{attribute.v8_set_return_value}};
     {% endif %}
 }
@@ skipping 231 matching lines @@
     {% endif %}
     {% if attribute.has_custom_setter %}
     {{v8_class}}::{{attribute.name}}AttributeSetterCustom(v8Value, info);
     {% else %}
     {{cpp_class}}V8Internal::{{attribute.name}}AttributeSetter{{world_suffix}}(v8Value, info);
     {% endif %}
     TRACE_EVENT_SET_SAMPLING_STATE("v8", "V8Execution");
 }
 {% endfilter %}
 {% endmacro %}