bindings: Add support for the record<K,V> WebIDL type.

third_party/WebKit/Source/bindings/core/v8/ToV8.h

 // Copyright 2014 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 ToV8_h
 #define ToV8_h
 
 // ToV8() provides C++ -> V8 conversion. Note that ToV8() can return an empty
 // handle. Call sites must check IsEmpty() before using return value.
 
@@ skipping 213 matching lines @@
   return toV8SequenceInternal(value, creationContext, isolate);
 }
 
 template <typename T, size_t inlineCapacity>
 inline v8::Local<v8::Value> ToV8(const HeapVector<T, inlineCapacity>& value,
                                  v8::Local<v8::Object> creationContext,
                                  v8::Isolate* isolate) {
   return toV8SequenceInternal(value, creationContext, isolate);
 }
 
+// The following two overloads are also used to convert record<K,V> IDL types
+// back into ECMAScript Objects.
 template <typename T>
 inline v8::Local<v8::Value> ToV8(const Vector<std::pair<String, T>>& value,
                                  v8::Local<v8::Object> creationContext,
                                  v8::Isolate* isolate) {
   v8::Local<v8::Object> object;
   {
     v8::Context::Scope contextScope(creationContext->CreationContext());
     object = v8::Object::New(isolate);
   }
   for (unsigned i = 0; i < value.size(); ++i) {
@@ skipping 77 matching lines @@
 // Cannot define in ScriptValue because of the circular dependency between toV8
 // and ScriptValue
 template <typename T>
 inline ScriptValue ScriptValue::from(ScriptState* scriptState, T&& value) {
   return ScriptValue(scriptState, ToV8(std::forward<T>(value), scriptState));
 }
 
 }  // namespace blink
 
 #endif  // ToV8_h