Componentization: add toV8(void*,...) to check function overload mismatch.

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 219 matching lines @@
     v8::Local<v8::Object> object = v8::Object::New(isolate);
     for (unsigned i = 0; i < value.size(); ++i) {
         v8::Local<v8::Value> v8Value = toV8(value[i].second, creationContext, isolate);
         if (v8Value.IsEmpty())
             v8Value = v8::Undefined(isolate);
         object->Set(v8String(isolate, value[i].first), v8Value);
     }
     return object;
 }
 
+// Only declare toV8(void*,...) for checking function overload mismatch.
+// This toV8(void*,...) should be never used. So we will find mismatch
+// because of "unresolved external symbol".
+// Without toV8(void*, ...), call to toV8 with T* will match with
+// toV8(bool, ...) if T is not a subclass of ScriptWrappable or if T is
+// declared but not defined (so it's not clear that T is a subclass of
+// ScriptWrappable).
+// This hack helps detect such unwanted implicit conversions from T* to bool.
+v8::Handle<v8::Value> toV8(void* value, v8::Handle<v8::Object> creationContext, v8::Isolate*);
+
 } // namespace blink
 
 #endif // ToV8_h