bindings: Supports [Replaceable] accessors.

Source/bindings/templates/attributes.cpp

Index: Source/bindings/templates/attributes.cpp
diff --git a/Source/bindings/templates/attributes.cpp b/Source/bindings/templates/attributes.cpp
index f7bc807acd6fcd53e79afed39c967926936fb1f9..b34c87c096ef8699a1faeda9e361ed848af1b7c5 100644
--- a/Source/bindings/templates/attributes.cpp
+++ b/Source/bindings/templates/attributes.cpp
@@ -211,7 +211,7 @@ v8::Local<v8::Value> v8Value, const v8::PropertyCallbackInfo<void>& info
     {% set cpp_class, v8_class = 'Element', 'V8Element' %}
     {% endif %}
     {# Local variables #}
-    {% if not attribute.is_static %}
+    {% if not attribute.is_static and not attribute.is_replaceable %}

[haraken, 2015/02/23 14:48:52]

For readability, it seems better to remove this branch. You can directly write
"v8::Local<v8::Object> holder = info.Holder()" just before where you actually
need the |holder|.

[Yuki, 2015/02/23 15:18:42]

Most of attributes need |holder|.  Only static attribute and replaceable
attribute do not need the holder.  Removing this branch makes things very
difficult, I think.

For example, line 218 and line 225, 243 use |holder|.  It's hard to write
"holder = info.Holder()" just before them without duplication.

     v8::Local<v8::Object> holder = info.Holder();
     {% endif %}
     {% if attribute.has_setter_exception_state %}
@@ -226,6 +226,19 @@ v8::Local<v8::Value> v8Value, const v8::PropertyCallbackInfo<void>& info
     {{attribute.cpp_type}} impl = WTF::getPtr(proxyImpl->{{attribute.name}}());
     if (!impl)
         return;
+    {% elif attribute.is_replaceable %}
+    {% if is_check_security %}

[haraken, 2015/02/23 14:48:52]

Why do we have the is_check_security clause only in the attribute.is_replaceable
clause? I guess the is_check_security clause would be needed in other clauses
(e.g., the attribute.put_forwards clause) as well.

[Yuki, 2015/02/23 15:18:42]

The code was copied from
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

I've not yet investigated about PutForwards.  I'll fix it if we need the check
for PutForwards, too, when I work on PutForwards.

However, PutForwards delegates the assignment to another attribute, so it's
possible that it's not the same as Replaceable.

+    {{cpp_class}}* impl = {{v8_class}}::toImpl(info.Holder());
+    ExceptionState exceptionState(ExceptionState::SetterContext, "{{attribute.name}}", "{{interface_name}}", info.Holder(), info.GetIsolate());
+    if (!BindingSecurity::shouldAllowAccessToFrame(info.GetIsolate(), impl->frame(), exceptionState)) {
+        exceptionState.throwIfNeeded();
+        return;
+    }
+    {% endif %}
+    if (info.This()->IsObject()) {
+        v8::Local<v8::String> propertyName = v8AtomicString(info.GetIsolate(), "{{attribute.name}}");
+        v8::Local<v8::Object>::Cast(info.This())->ForceSet(propertyName, v8Value);
+    }
     {% elif not attribute.is_static %}
     {{cpp_class}}* impl = {{v8_class}}::toImpl(holder);
     {% endif %}
@@ -235,7 +248,9 @@ v8::Local<v8::Value> v8Value, const v8::PropertyCallbackInfo<void>& info
     {% endif %}
     {# Convert JS value to C++ value #}
     {% if attribute.idl_type != 'EventHandler' %}
+    {% if attribute.v8_value_to_local_cpp_value %}
     {{attribute.v8_value_to_local_cpp_value}};
+    {% endif %}
     {% elif not is_node %}{# EventHandler hack #}
     moveEventListenerToNewWrapper(info.GetIsolate(), holder, {{attribute.event_handler_getter_expression}}, v8Value, {{v8_class}}::eventListenerCacheIndex);
     {% endif %}
@@ -268,7 +283,9 @@ v8::Local<v8::Value> v8Value, const v8::PropertyCallbackInfo<void>& info
     ExecutionContext* executionContext = currentExecutionContext(info.GetIsolate());
     {% endif %}
     {# Set #}
+    {% if attribute.cpp_setter %}
     {{attribute.cpp_setter}};
+    {% endif %}
     {# Post-set #}
     {% if attribute.is_setter_raises_exception %}
     exceptionState.throwIfNeeded();