Prevent calls to ReturnValue::Set with pointer-valued types.

Currently, this code will compile:
  SomePointer* p = ...;
  ReturnValue r = ...;
  r.Set(p);

What happens is that ReturnValue::Set has no pointer-ish overloads, but
a bool one, and hence C++ will convert the pointer to a bool and use
the Set(bool) overload. In other words, the example above is equivalent
to: r.Set(p ? true : false); Which probably isn't what the author had
in mind. This change adds a Set(void*) overload whose body forces a
compile error, to prevent this from happening inadvertently. The only
use of this indeed turned out to be an error.

(Wait for issue 364025 before submitting.)

BUG=
R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/240013004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21217 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

include/v8.h

@@ -2429,6 +2429,9 @@ class ReturnValue {
   // Convenience getter for Isolate
   V8_INLINE Isolate* GetIsolate();
 
+  // Pointer setter: Uncompilable to prevent inadvertent misuse.
+  void Set(void* whatever);
+
  private:
   template<class F> friend class ReturnValue;
   template<class F> friend class FunctionCallbackInfo;
@@ -5973,6 +5976,12 @@ Isolate* ReturnValue<T>::GetIsolate() {
   return *reinterpret_cast<Isolate**>(&value_[-2]);
 }
 
+template<typename T>
+void ReturnValue<T>::Set(void* whatever) {
+  // Uncompilable to prevent inadvertent misuse.
+  TYPE_CHECK(void*, Primitive);
+}
+
 template<typename T>
 internal::Object* ReturnValue<T>::GetDefaultValue() {
   // Default value is always the pointer below value_ on the stack.