[api] Deprecate old tasks API

It was marked V8_DEPRECATE_SOON in https://crrev.com/c/1261936 (part of
M-71).

R=ahaas@chromium.org, ulan@chromium.org

Bug: v8:9810
Change-Id: I64a7937b518dbf2a75361bbbecd514618922d543
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1849523Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64273}

include/v8-platform.h

@@ -367,8 +367,7 @@ class Platform {
    * |isolate|. Tasks posted for the same isolate should be execute in order of
    * scheduling. The definition of "foreground" is opaque to V8.
    */
-  V8_DEPRECATE_SOON(
-      "Use a taskrunner acquired by GetForegroundTaskRunner instead.")
+  V8_DEPRECATED("Use a taskrunner acquired by GetForegroundTaskRunner instead.")
   virtual void CallOnForegroundThread(Isolate* isolate, Task* task) = 0;
 
   /**
@@ -377,8 +376,7 @@ class Platform {
    * Tasks posted for the same isolate should be execute in order of
    * scheduling. The definition of "foreground" is opaque to V8.
    */
-  V8_DEPRECATE_SOON(
-      "Use a taskrunner acquired by GetForegroundTaskRunner instead.")
+  V8_DEPRECATED("Use a taskrunner acquired by GetForegroundTaskRunner instead.")
   virtual void CallDelayedOnForegroundThread(Isolate* isolate, Task* task,
                                              double delay_in_seconds) = 0;
 
@@ -390,8 +388,7 @@ class Platform {
    * starved for an arbitrarily long time if no idle time is available.
    * The definition of "foreground" is opaque to V8.
    */
-  V8_DEPRECATE_SOON(
-      "Use a taskrunner acquired by GetForegroundTaskRunner instead.")
+  V8_DEPRECATED("Use a taskrunner acquired by GetForegroundTaskRunner instead.")
   virtual void CallIdleOnForegroundThread(Isolate* isolate, IdleTask* task) {
     // This must be overriden if |IdleTasksEnabled()|.
     abort();