Fix crash by disabling problematic functionalitie (VerifyPointers)

runtime/vm/custom_isolate_test.cc

Index: runtime/vm/custom_isolate_test.cc
diff --git a/runtime/vm/custom_isolate_test.cc b/runtime/vm/custom_isolate_test.cc
index 1995ee651c4e50723d34aa9997487f4660c895e8..03c57732f00838261d7a44dd9598c8f7c55618ea 100644
--- a/runtime/vm/custom_isolate_test.cc
+++ b/runtime/vm/custom_isolate_test.cc
@@ -324,6 +324,12 @@ UNIT_TEST_CASE(CustomIsolates) {
 #ifdef DEBUG
   FLAG_verify_on_transition = true;
 #endif
+  // Cannot verify heap while running compilation in background.
+  // Issue #26149.
+  FLAG_background_compilation = false;
+  // Issue #26150.
+  FLAG_use_osr = false;
+
   event_queue = new EventQueue();
 
   Dart_Isolate dart_isolate = TestCase::CreateTestIsolate();