[api] Minor improvement to documentation for kNonMasking.

test/cctest/test-api-interceptors.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stdlib.h>
 
 #include "test/cctest/test-api.h"
 
 #include "include/v8-util.h"
 #include "src/api.h"
@@ skipping 4320 matching lines @@
 
   auto interceptor =
       interceptor_templ->NewInstance(context.local()).ToLocalChecked();
   context->Global()
       ->Set(context.local(), v8_str("obj"), interceptor)
       .FromJust();
 
   ExpectInt32("obj.whatever", 239);
 
   CompileRun("obj.whatever = 4;");
+
+  // obj.whatever exists, thus it is not affected by the non-masking
+  // interceptor.
   ExpectInt32("obj.whatever", 4);
 
   CompileRun("delete obj.whatever;");
   ExpectInt32("obj.whatever", 239);
 }
 
 
 THREADED_TEST(NonMaskingInterceptorPrototypeProperty) {
   auto isolate = CcTest::isolate();
   v8::HandleScope handle_scope(isolate);
@@ skipping 183 matching lines @@
             ->Set(env.local(), v8_str("Fun"),
                   fun_templ->GetFunction(env.local()).ToLocalChecked())
             .FromJust());
 
   CompileRun(
       "var f = new Fun();"
       "Number.prototype.__proto__ = f;"
       "var a = 42;"
       "for (var i = 0; i<3; i++) { a.foo; }");
 }