Fix from Paul Lind that helps post-isolates V8 work with older

Android releases.  See http://code.google.com/p/v8/issues/detail?id=1780
Review URL: http://codereview.chromium.org/8347032

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9689 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/api.cc

@@ -4005,14 +4005,15 @@ void v8::V8::GetHeapStatistics(HeapStatistics* heap_statistics) {
 bool v8::V8::IdleNotification() {
   // Returning true tells the caller that it need not
   // continue to call IdleNotification.
-  if (!i::Isolate::Current()->IsInitialized()) return true;
+  i::Isolate* isolate = i::Isolate::Current();
+  if (isolate == NULL || !isolate->IsInitialized()) return true;
   return i::V8::IdleNotification();
 }
 
 
 void v8::V8::LowMemoryNotification() {
   i::Isolate* isolate = i::Isolate::Current();
-  if (!isolate->IsInitialized()) return;
+  if (isolate == NULL || !isolate->IsInitialized()) return;
   isolate->heap()->CollectAllAvailableGarbage();
 }