Revert "Revert "Upgrade to 5.0.71.48"" DO NOT MERGE

This reverts commit f2e3994fa5148cc3d9946666f0b0596290192b0e,
and updates the x64 makefile properly so it doesn't break that
build.

FPIIM-449

Change-Id: Ib83e35bfbae6af627451c926a9650ec57c045605
(cherry picked from commit 109988c7ccb6f3fd1a58574fa3dfb88beaef6632)
diff --git a/src/optimizing-compile-dispatcher.cc b/src/optimizing-compile-dispatcher.cc
index 7062db6..4836b9b 100644
--- a/src/optimizing-compile-dispatcher.cc
+++ b/src/optimizing-compile-dispatcher.cc
@@ -7,6 +7,7 @@
 #include "src/base/atomicops.h"
 #include "src/full-codegen/full-codegen.h"
 #include "src/isolate.h"
+#include "src/tracing/trace-event.h"
 #include "src/v8.h"
 
 namespace v8 {
@@ -59,6 +60,7 @@
         isolate_->optimizing_compile_dispatcher();
     {
       TimerEventScope<TimerEventRecompileConcurrent> timer(isolate_);
+      TRACE_EVENT0("v8", "V8.RecompileConcurrent");
 
       if (dispatcher->recompilation_delay_ != 0) {
         base::OS::Sleep(base::TimeDelta::FromMilliseconds(
@@ -244,9 +246,9 @@
         }
         DisposeOptimizedCompileJob(job, false);
       } else {
-        Handle<Code> code = Compiler::GetConcurrentlyOptimizedCode(job);
+        MaybeHandle<Code> code = Compiler::GetConcurrentlyOptimizedCode(job);
         function->ReplaceCode(code.is_null() ? function->shared()->code()
-                                             : *code);
+                                             : *code.ToHandleChecked());
       }
     }
   }