Remove support for object grouping during Garbage Collection

runtime/vm/thread_test.cc

Index: runtime/vm/thread_test.cc
diff --git a/runtime/vm/thread_test.cc b/runtime/vm/thread_test.cc
index 2a8e8d7a6a039aaa4928959e007ea25bb04552e5..ec998f8980d16df6d998e1b3045f6a8a540c7d4c 100644
--- a/runtime/vm/thread_test.cc
+++ b/runtime/vm/thread_test.cc
@@ -134,7 +134,6 @@ class TaskWithZoneAllocation : public ThreadPool::Task {
         // Ensure that our particular zone is visited.
         isolate_->IterateObjectPointers(
             &counter,
-            /* visit_prologue_weak_handles = */ true,
             StackFrameIterator::kValidateFrames);
         EXPECT_EQ(1, counter.count());
       }
@@ -152,7 +151,6 @@ class TaskWithZoneAllocation : public ThreadPool::Task {
         // Ensure that our particular zone is visited.
         isolate_->IterateObjectPointers(
             &str_counter,
-            /* visit_prologue_weak_handles = */ true,
             StackFrameIterator::kValidateFrames);
         // We should visit the string object exactly once.
         EXPECT_EQ(1, str_counter.count());
@@ -279,7 +277,6 @@ class SafepointTestTask : public ThreadPool::Task {
         ObjectCounter counter(isolate_, &smi);
         isolate_->IterateObjectPointers(
             &counter,
-            /* visit_prologue_weak_handles = */ true,
             StackFrameIterator::kValidateFrames);
         {
           MutexLocker ml(mutex_);