v8: unbreak make native build

The security fix from commit 6b92a71 also back-ported the test case.
Said test case relies on API that is only available in newer versions
of V8 and, as a result, broke the `make native` and `make <arch.mode>`
builds.  This commit reverts that part of the back-port.  Fixes the
following build error:

  ../test/cctest/test-api.cc: In function ‘void TestRegress260106()’:
  ../test/cctest/test-api.cc:17712:34: error: ‘class v8::Context’ has
  no member named ‘GetIsolate’

deps/v8/test/cctest/test-api.cc

@@ -17707,17 +17707,6 @@ THREADED_TEST(Regress157124) {
 }
 
 
-THREADED_TEST(Regress260106) {
-  LocalContext context;
-  v8::HandleScope scope(context->GetIsolate());
-  Local<FunctionTemplate> templ = FunctionTemplate::New(DummyCallHandler);
-  CompileRun("for (var i = 0; i < 128; i++) Object.prototype[i] = 0;");
-  Local<Function> function = templ->GetFunction();
-  CHECK(!function.IsEmpty());
-  CHECK(function->IsFunction());
-}
-
-
 #ifndef WIN32
 class ThreadInterruptTest {
  public: