IDL: Drop value conversion (V8 -> C++) macros from generated code

Source/bindings/tests/results/modules/UnionTypesModules.cpp

Index: Source/bindings/tests/results/modules/UnionTypesModules.cpp
diff --git a/Source/bindings/tests/results/modules/UnionTypesModules.cpp b/Source/bindings/tests/results/modules/UnionTypesModules.cpp
index 6438e18dd44c7c5b7e81fde3f33ddab95f11f56b..5d55aa9bf9c14c089c7e915a91bd83ecf59d4195 100644
--- a/Source/bindings/tests/results/modules/UnionTypesModules.cpp
+++ b/Source/bindings/tests/results/modules/UnionTypesModules.cpp
@@ -55,20 +55,20 @@ BooleanOrString BooleanOrString::fromString(String value)
     return container;
 }
 
-void V8BooleanOrString::toImpl(v8::Isolate* isolate, v8::Local<v8::Value> v8Value, BooleanOrString& impl, ExceptionState& exceptionState)
+bool V8BooleanOrString::toImpl(v8::Isolate* isolate, v8::Local<v8::Value> v8Value, BooleanOrString& impl, ExceptionState& exceptionState)
 {
     if (v8Value.IsEmpty())
-        return;
+        return true;
 
     if (v8Value->IsBoolean()) {
         impl.setBoolean(v8Value->ToBoolean()->Value());
-        return;
+        return true;
     }
 
     {
-        TOSTRING_VOID_EXCEPTIONSTATE(V8StringResource<>, cppValue, v8Value, exceptionState);
+        TONATIVE_DECLARE(V8StringResource<>, cppValue, (cppValue = v8Value).prepare(exceptionState), return false);
         impl.setString(cppValue);
-        return;
+        return true;
     }
 
 }