Add V8ObjectBuilder helper and use in modules/crypto/

Source/bindings/core/v8/V8ObjectBuilder.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8ObjectBuilder_h
+#define V8ObjectBuilder_h
+
+#include "wtf/text/WTFString.h"
+#include <v8.h>
+
+namespace blink {
+
+class ScriptValue;
+
+class V8ObjectBuilder {

[haraken, 2015/03/24 14:33:33]

Can we add STACK_ALLOCATED?

[Jens Widell, 2015/03/24 15:16:29]

Done.

[Jens Widell, 2015/03/24 16:22:37]

Actually this was a bit problematic. (I didn't notice since I don't build with
clang locally.)

V8ObjectBuilder is used as a member in DictionaryBuilder (CryptoKey.cpp) which
then needs STACK_ALLOCATED() too (I guess). But DictionaryBuilder inherits
WebCryptoKeyAlgorithmDictionary (public/platform/WebCryptoAlgorithmParams.h)
which I'm assuming we don't/can't add STACK_ALLOCATED() to.

Okay to drop STACK_ALLOCATED()?

+public:
+    V8ObjectBuilder(v8::Isolate*);

[haraken, 2015/03/24 14:33:33]

Add explicit.

[Jens Widell, 2015/03/24 15:16:29]

Done.

+
+    ScriptValue scriptValue() const;
+    v8::Local<v8::Object> v8Value() const { return m_object; }
+    v8::Isolate* isolate() const { return m_isolate; }
+
+    V8ObjectBuilder& add(String name, const ScriptValue&);
+    V8ObjectBuilder& add(String name, const V8ObjectBuilder&);
+
+    V8ObjectBuilder& addNull(String name);
+    V8ObjectBuilder& addBoolean(String name, bool value);
+    V8ObjectBuilder& addNumber(String name, double value);
+    V8ObjectBuilder& addString(String name, String value);

[haraken, 2015/03/24 14:33:33]

Nit: I'd call all of these functions "add".

[Jens Widell, 2015/03/24 14:51:46]

Including addNull()?

Also, I think this might produce an overloading issue for a use like

  builder.add("foo", 10);

since that can convert both to bool and double. I could of course add int and
unsigned overloads to solve that.

But then, a caller meaning to set a boolean property using a calculated value
will need to make sure the value expression's type is really bool, and not
something that would convert fine to a bool in a boolean context, but is
actually, say, an integer.

So, in summary, I would probably rather not rely on C++ overload resolution to
get the correct JS value type.

+
+private:
+    void add(String name, v8::Local<v8::Value>);
+
+    v8::Isolate* m_isolate;
+    v8::Local<v8::Object> m_object;
+};
+
+} // namespace blink
+
+#endif // V8ObjectBuilder_h