Revert "[vm] Expose Dart_{CurrentIsolate,ExitIsolate,EnterIsolate}"

This reverts commit a251281.

Reason for revert: FFI tests fail to link on Windows, fail to load on product-mode Android

Original change's description:
> [vm] Expose Dart_{CurrentIsolate,ExitIsolate,EnterIsolate}
>
> For applications that want to have arbitrary number of isolates call
> into native code that may be blocking, we expose the API functions that
> allows those native threads to exit an isolate before running
> long/blocking code.
>
> Without the ability to exit/re-enter isolate, one may experience
> deadlocks as we have a fixed limit on the number of concurrently
> executing isolates atm.
>
> In the longer term we may find a way to do this automatically
> with low overhead, see [0]. But since those API functions are quite
> stable and we already expose e.g. `Dart_{Enter,Exit}Scope`, I don't
> see a reason not to expose `Dart_{Enter,Exit}Isolate`.
>
> [0] Issue #51261
>
> Issue #51254
>
> TEST=ffi{,_2}/dl_api_exit_enter_isolate_test
>
> Change-Id: I91c772ca962fddb87919663fea07939a498fa205
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/292722
> Commit-Queue: Martin Kustermann <kustermann@google.com>
> Reviewed-by: Daco Harkes <dacoharkes@google.com>
> Reviewed-by: Ryan Macnak <rmacnak@google.com>

Change-Id: I05ad5b9ce24754a68693160e470f8eb71a812c75
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/294860
Auto-Submit: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>

runtime/bin/ffi_test/ffi_test_functions_vmspecific.cc

@@ -30,8 +30,6 @@
 #include <iostream>
 #include <limits>
 
-#include "bin/lockers.h"
-
 // TODO(dartbug.com/40579): This requires static linking to either link
 // dart.exe or dart_precompiled_runtime.exe on Windows.
 // The sample currently fails on Windows in AOT mode.
@@ -422,6 +420,16 @@ DART_EXPORT intptr_t InitDartApiDL(void* data) {
 //
 // sample_async_callback.dart
 
+void Fatal(char const* file, int line, char const* error) {
+  printf("FATAL %s:%i\n", file, line);
+  printf("%s\n", error);
+  Dart_DumpNativeStackTrace(nullptr);
+  Dart_PrepareToAbort();
+  abort();
+}
+
+#define FATAL(error) Fatal(__FILE__, __LINE__, error)
+
 DART_EXPORT void SleepOnAnyOS(intptr_t seconds) {
 #if defined(DART_HOST_OS_WINDOWS)
   Sleep(1000 * seconds);
@@ -1274,28 +1282,6 @@ DART_EXPORT void SetFfiNativeResolverForTest(Dart_Handle url) {
   ENSURE(!Dart_IsError(result));
 }
 
-DART_EXPORT void WaitUntilNThreadsEnterBarrier(intptr_t num_threads) {
-  Dart_Isolate isolate = Dart_CurrentIsolate_DL();
-  Dart_ExitIsolate_DL();
-  {
-    ENSURE(Dart_CurrentIsolate_DL() == nullptr);
-
-    // Guaranteed to be initialized exactly once (no race between multiple
-    // threads).
-    static dart::bin::Monitor monitor;
-    static intptr_t thread_count = 0;
-
-    dart::bin::MonitorLocker ml(&monitor);
-    ++thread_count;
-    while (thread_count < num_threads) {
-      ml.Wait();
-    }
-    if (thread_count != num_threads) UNREACHABLE();
-    ml.NotifyAll();
-  }
-  Dart_EnterIsolate_DL(isolate);
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 // Helper for the regression test for b/216834909
 ////////////////////////////////////////////////////////////////////////////////

runtime/include/dart_api_dl.h

@@ -90,10 +90,6 @@ typedef void (*Dart_NativeMessageHandler_DL)(Dart_Port_DL dest_port_id,
   F(Dart_UpdateFinalizableExternalSize, void,                                  \
     (Dart_FinalizableHandle object, Dart_Handle strong_ref_to_object,          \
      intptr_t external_allocation_size))                                       \
-  /* Isolates */                                                               \
-  F(Dart_CurrentIsolate, Dart_Isolate, (void))                                 \
-  F(Dart_ExitIsolate, void, (void))                                            \
-  F(Dart_EnterIsolate, void, (Dart_Isolate))                                   \
   /* Dart_Port */                                                              \
   F(Dart_Post, bool, (Dart_Port_DL port_id, Dart_Handle object))               \
   F(Dart_NewSendPort, Dart_Handle, (Dart_Port_DL port_id))                     \

runtime/include/dart_version.h

@@ -11,6 +11,6 @@
 // On backwards compatible changes the minor version is increased.
 // The versioning covers the symbols exposed in dart_api_dl.h
 #define DART_API_DL_MAJOR_VERSION 2
-#define DART_API_DL_MINOR_VERSION 3
+#define DART_API_DL_MINOR_VERSION 2
 
 #endif /* RUNTIME_INCLUDE_DART_VERSION_H_ */ /* NOLINT */