Revert "Adopt to new MicrotasksCompletedCallback signature"

This reverts commit 1bda93b7.

Reason for revert: Blocks roll of V8 https://chromium-review.googlesource.com/c/chromium/src/+/1508095/1

Original change's description:
> Adopt to new MicrotasksCompletedCallback signature
> 
> V8 updated the signature of MicrotasksCompletedCallback to take a void
> pointer user data, and is deprecating the old signature.
> This CL updates its user to use the new one.
> 
> Change-Id: I24990f68b2964fa80554689947746636958f59cc
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1504660
> Reviewed-by: Kentaro Hara <haraken@chromium.org>
> Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
> Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#638471}

TBR=peria@chromium.org,haraken@chromium.org,tzik@chromium.org

Change-Id: I7a5134b417be5c8b2e189e30a488ce09929d5e6e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1507875Reviewed-by: Michael Hablich <hablich@chromium.org>
Commit-Queue: Michael Hablich <hablich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638531}

third_party/blink/renderer/platform/bindings/v8_per_isolate_data.cc

@@ -67,7 +67,7 @@ static void BeforeCallEnteredCallback(v8::Isolate* isolate) {
   CHECK(!ScriptForbiddenScope::IsScriptForbidden());
 }
 
-static void MicrotasksCompletedCallback(v8::Isolate* isolate, void*) {
+static void MicrotasksCompletedCallback(v8::Isolate* isolate) {
   V8PerIsolateData::From(isolate)->RunEndOfScopeTasks();
 }