[cleanup] Remove unneeded reinterpret_cast

Came across this cast while checking a CFI issue. It reinterpret_casts
between two identical function pointers, so it is redundant.

R=ulan@chromium.org

Bug: v8:7570
Change-Id: I2d92e93788027e41abdb12af8371251c0da6a709
Reviewed-on: https://chromium-review.googlesource.com/1004674Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52507}

src/global-handles.cc

@@ -270,10 +270,8 @@ class GlobalHandles::Node {
     // Zap with something dangerous.
     *location() = reinterpret_cast<Object*>(0x6057CA11);
 
-    typedef v8::WeakCallbackInfo<void> Data;
-    auto callback = reinterpret_cast<Data::Callback>(weak_callback_);
-    pending_phantom_callbacks->push_back(
-        PendingPhantomCallback(this, callback, parameter(), embedder_fields));
+    pending_phantom_callbacks->push_back(PendingPhantomCallback(
+        this, weak_callback_, parameter(), embedder_fields));
     DCHECK(IsInUse());
     set_state(NEAR_DEATH);
   }