Clean up issues raised on previous CL.

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 76801619e9f0507e5a3561fcceb01b89a75879d5..94e4d3d4247823143e6cfca3f612e5b1e7cd8ca7 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -527,7 +527,7 @@ class Isolate {
     DCHECK(base::Relaxed_Load(&isolate_key_created_) == 1);
     Isolate* isolate = reinterpret_cast<Isolate*>(
         base::Thread::GetExistingThreadLocal(isolate_key_));
-    DCHECK(isolate != NULL);
+    DCHECK_NOT_NULL(isolate);
     return isolate;
   }
 
@@ -871,8 +871,8 @@ class Isolate {
   Counters* counters() {
     // Call InitializeLoggingAndCounters() if logging is needed before
     // the isolate is fully initialized.
-    DCHECK(counters_ != NULL);
-    return counters_;
+    DCHECK_NOT_NULL(counters_shared_.get());
+    return counters_shared_.get();
   }
   std::shared_ptr<Counters> counters_shared() { return counters_shared_; }
   RuntimeProfiler* runtime_profiler() { return runtime_profiler_; }
@@ -880,7 +880,7 @@ class Isolate {
   Logger* logger() {
     // Call InitializeLoggingAndCounters() if logging is needed before
     // the isolate is fully initialized.
-    DCHECK(logger_ != NULL);
+    DCHECK_NOT_NULL(logger_);
     return logger_;
   }
   StackGuard* stack_guard() { return &stack_guard_; }
@@ -1431,7 +1431,6 @@ class Isolate {
   RuntimeProfiler* runtime_profiler_;
   CompilationCache* compilation_cache_;
   std::shared_ptr<Counters> counters_shared_;
-  Counters* counters_;
   base::RecursiveMutex break_access_;
   Logger* logger_;
   StackGuard stack_guard_;