bindings: Use Maybe APIs in ScriptPromise

Source/bindings/core/v8/ScriptValue.h

Index: Source/bindings/core/v8/ScriptValue.h
diff --git a/Source/bindings/core/v8/ScriptValue.h b/Source/bindings/core/v8/ScriptValue.h
index 7ad2aecaed7c51507d12e55ea33d1dd2cecd2704..d234a9783aa9402e8eb8ed1805f85691b89b1571 100644
--- a/Source/bindings/core/v8/ScriptValue.h
+++ b/Source/bindings/core/v8/ScriptValue.h
@@ -67,6 +67,14 @@ public:
         ASSERT(isEmpty() || m_scriptState);

[haraken, 2015/03/25 05:08:29]

I'm just wondering but is it valid that m_scriptState is 0 here? (You can
address this in a follow-up.)

[bashi, 2015/03/25 07:25:32]

You mean we should just ASSERT(m_scriptState)? I think it makes sense.

[bashi, 2015/03/25 07:35:01]

It seems that some tests fail when dropping isEmpty(), so I'll keep the current
condition.

[haraken, 2015/03/25 09:04:23]

Thanks for the investigation. Yeah, if the value is empty, the value doesn't
need to be associated with any ScriptState, so allowing no ScriptState when the
value is empty would make sense. Sorry about the noise.

     }
 
+    template <typename T>
+    ScriptValue(ScriptState* scriptState, v8::MaybeLocal<T> value)
+        : m_scriptState(scriptState)
+        , m_value(value.IsEmpty() ? nullptr : SharedPersistent<v8::Value>::create(value.ToLocalChecked(), scriptState->isolate()))
+    {
+        ASSERT(isEmpty() || m_scriptState);

[haraken, 2015/03/25 05:08:29]

Ditto.

+    }
+
     ScriptValue(const ScriptValue& value)
         : m_scriptState(value.m_scriptState)
         , m_value(value.m_value)
@@ -84,6 +92,12 @@ public:
         return m_scriptState ? m_scriptState->isolate() : v8::Isolate::GetCurrent();
     }
 
+    v8::Local<v8::Context> context() const
+    {
+        ASSERT(m_scriptState.get());
+        return m_scriptState->context();
+    }
+
     ScriptValue& operator=(const ScriptValue& value)
     {
         if (this != &value) {