Reland "[vm] Cleanup unused code in ClosureFunctionsCache"

This is a reland of commit 4c1235c

The underlying problem is addressed in https://dart-review.googlesource.com/c/sdk/+/262429.

Original change's description:
> [vm] Cleanup unused code in ClosureFunctionsCache
>
> TEST=ci
>
> Change-Id: Ia6f24545c7e2d5b0df81cab52585d17556b36c16
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/256363
> Commit-Queue: Ryan Macnak <[email protected]>
> Reviewed-by: Ryan Macnak <[email protected]>
> Auto-Submit: Alexander Markov <[email protected]>

TEST=ci
Change-Id: I96bd99174e68818ca8024e72836ebd1c99cdecd5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/263141
Reviewed-by: Tess Strickland <[email protected]>
Reviewed-by: Ryan Macnak <[email protected]>
Commit-Queue: Alexander Markov <[email protected]>

Author: alexmarkov

runtime/vm/closure_functions_cache.cc

@@ -10,37 +10,6 @@
 
 namespace dart {
 
-FunctionPtr ClosureFunctionsCache::LookupClosureFunction(
-    const Class& owner,
-    TokenPosition token_pos) {
-  auto thread = Thread::Current();
-  SafepointReadRwLocker ml(thread, thread->isolate_group()->program_lock());
-  return LookupClosureFunctionLocked(owner, token_pos);
-}
-
-FunctionPtr ClosureFunctionsCache::LookupClosureFunctionLocked(
-    const Class& owner,
-    TokenPosition token_pos) {
-  auto thread = Thread::Current();
-  auto zone = thread->zone();
-  auto object_store = thread->isolate_group()->object_store();
-
-  DEBUG_ASSERT(
-      thread->isolate_group()->program_lock()->IsCurrentThreadReader());
-
-  const auto& closures =
-      GrowableObjectArray::Handle(zone, object_store->closure_functions());
-  auto& closure = Function::Handle(zone);
-  intptr_t num_closures = closures.Length();
-  for (intptr_t i = 0; i < num_closures; i++) {
-    closure ^= closures.At(i);
-    if (closure.token_pos() == token_pos && closure.Owner() == owner.ptr()) {
-      return closure.ptr();
-    }
-  }
-  return Function::null();
-}
-
 FunctionPtr ClosureFunctionsCache::LookupClosureFunction(
     const Function& parent,
     TokenPosition token_pos) {
@@ -126,33 +95,6 @@ FunctionPtr ClosureFunctionsCache::ClosureFunctionFromIndex(intptr_t idx) {
   return Function::RawCast(closures_array.At(idx));
 }
 
-FunctionPtr ClosureFunctionsCache::GetUniqueInnerClosure(
-    const Function& outer) {
-  auto thread = Thread::Current();
-  auto zone = thread->zone();
-  auto object_store = thread->isolate_group()->object_store();
-
-  SafepointReadRwLocker ml(thread, thread->isolate_group()->program_lock());
-
-  const auto& closures =
-      GrowableObjectArray::Handle(zone, object_store->closure_functions());
-  auto& entry = Function::Handle(zone);
-  for (intptr_t i = (closures.Length() - 1); i >= 0; i--) {
-    entry ^= closures.At(i);
-    if (entry.parent_function() == outer.ptr()) {
-#if defined(DEBUG)
-      auto& other = Function::Handle(zone);
-      for (intptr_t j = i - 1; j >= 0; j--) {
-        other ^= closures.At(j);
-        ASSERT(other.parent_function() != outer.ptr());
-      }
-#endif
-      return entry.ptr();
-    }
-  }
-  return Function::null();
-}
-
 void ClosureFunctionsCache::ForAllClosureFunctions(
     std::function<bool(const Function&)> callback) {
   auto thread = Thread::Current();

runtime/vm/closure_functions_cache.h

@@ -39,11 +39,6 @@ class FunctionPtr;
 // requirements above).
 class ClosureFunctionsCache : public AllStatic {
  public:
-  static FunctionPtr LookupClosureFunction(const Class& owner,
-                                           TokenPosition pos);
-  static FunctionPtr LookupClosureFunctionLocked(const Class& owner,
-                                                 TokenPosition pos);
-
   static FunctionPtr LookupClosureFunction(const Function& parent,
                                            TokenPosition token_pos);
   static FunctionPtr LookupClosureFunctionLocked(const Function& parent,
@@ -60,8 +55,6 @@ class ClosureFunctionsCache : public AllStatic {
   static intptr_t FindClosureIndex(const Function& needle);
   static FunctionPtr ClosureFunctionFromIndex(intptr_t idx);
 
-  static FunctionPtr GetUniqueInnerClosure(const Function& outer);
-
   // Visits all closure functions registered in the object store.
   //
   // Iterates in-order, thereby allowing new closures being added during the