Remove support for pretenuring as it is not fully implemented and is currently turned on for a very…

runtime/vm/assembler_x64.cc

Index: runtime/vm/assembler_x64.cc
diff --git a/runtime/vm/assembler_x64.cc b/runtime/vm/assembler_x64.cc
index 67bc2379a7632291525a9f6c6f83d9d19b2a18f4..f7203162726adca15f91a6ba09e7e842f8565c8d 100644
--- a/runtime/vm/assembler_x64.cc
+++ b/runtime/vm/assembler_x64.cc
@@ -3523,7 +3523,7 @@ void Assembler::TryAllocate(const Class& cls,
     // allocation call site.
     MaybeTraceAllocation(cls.id(), failure, near_jump);
     const intptr_t instance_size = cls.instance_size();
-    Heap::Space space = Heap::SpaceForAllocation(cls.id());
+    Heap::Space space = Heap::kNew;
     movq(temp, Address(THR, Thread::heap_offset()));
     movq(instance_reg, Address(temp, Heap::TopOffset(space)));
     addq(instance_reg, Immediate(instance_size));
@@ -3561,7 +3561,7 @@ void Assembler::TryAllocateArray(intptr_t cid,
     // (i.e. the allocation stub) which will allocate the object and trace the
     // allocation call site.
     MaybeTraceAllocation(cid, failure, near_jump);
-    Heap::Space space = Heap::SpaceForAllocation(cid);
+    Heap::Space space = Heap::kNew;
     movq(temp, Address(THR, Thread::heap_offset()));
     movq(instance, Address(temp, Heap::TopOffset(space)));
     movq(end_address, instance);