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/contexts-inl.h b/src/contexts-inl.h
index 67257ae..c26ce5b 100644
--- a/src/contexts-inl.h
+++ b/src/contexts-inl.h
@@ -33,7 +33,8 @@
 Handle<Context> ScriptContextTable::GetContext(Handle<ScriptContextTable> table,
                                                int i) {
   DCHECK(i < table->used());
-  return Handle<Context>::cast(FixedArray::get(table, i + kFirstContextSlot));
+  return Handle<Context>::cast(
+      FixedArray::get(*table, i + kFirstContextSlot, table->GetIsolate()));
 }