Move libplatform files into v8::platform namespace

src/libplatform/task-queue.cc

Index: src/libplatform/task-queue.cc
diff --git a/src/libplatform/task-queue.cc b/src/libplatform/task-queue.cc
index a5d08f1a14dbc9b1bb62f45d631219cccf0ab5cd..0158830cced55c1cb6d9fc8ef18e437a348fcfa0 100644
--- a/src/libplatform/task-queue.cc
+++ b/src/libplatform/task-queue.cc
@@ -7,7 +7,7 @@
 #include "src/base/logging.h"
 
 namespace v8 {
-namespace internal {
+namespace platform {
 
 TaskQueue::TaskQueue() : process_queue_semaphore_(0), terminated_(false) {}
 
@@ -53,4 +53,4 @@ void TaskQueue::Terminate() {
   process_queue_semaphore_.Signal();
 }
 
-} }  // namespace v8::internal
+} }  // namespace v8::platform