[vm] Remove dart:cli waitFor

Closes https://github.com/dart-lang/sdk/issues/52121

Tested: CI
CoreLibraryReviewExempt: Approved breaking change to VM specific code
Change-Id: Icc89017c5a7676c2ae07488692ad8b8b9e131a7f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/354880
Commit-Queue: Slava Egorov <vegorov@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>

runtime/include/dart_api.h

@@ -868,7 +868,7 @@ typedef struct Dart_CodeObserver {
  * implement registration of kernel blobs for the subsequent Isolate.spawnUri
  * If no callback is provided, the registration of kernel blobs will throw
  * an error.
- * 
+ *
  * \param kernel_buffer A buffer which contains a kernel program. Callback
  *                      should copy the contents of `kernel_buffer` as
  *                      it may be freed immediately after registration.
@@ -888,7 +888,7 @@ typedef const char* (*Dart_RegisterKernelBlobCallback)(
  * unregister kernel blobs.
  * If no callback is provided, the unregistration of kernel blobs will throw
  * an error.
- * 
+ *
  * \param kernel_blob_uri URI of the kernel blob to unregister.
  */
 typedef void (*Dart_UnregisterKernelBlobCallback)(const char* kernel_blob_uri);
@@ -1679,17 +1679,6 @@ DART_EXPORT Dart_Handle Dart_GetStickyError(void);
  */
 DART_EXPORT DART_WARN_UNUSED_RESULT Dart_Handle Dart_HandleMessage(void);
 
-/**
- * Drains the microtask queue, then blocks the calling thread until the current
- * isolate receives a message, then handles all messages.
- *
- * \param timeout_millis When non-zero, the call returns after the indicated
-          number of milliseconds even if no message was received.
- * \return A valid handle if no error occurs, otherwise an error handle.
- */
-DART_EXPORT DART_WARN_UNUSED_RESULT Dart_Handle
-Dart_WaitForEvent(int64_t timeout_millis);
-
 /**
  * Handles any pending messages for the vm service for the current
  * isolate.