Unboxed Float64x2 fields and some misc fixes

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 382dac2ca16413e891813f1c8e353508f8d3b2e1..3fb01ef7895dfaebfde6cca990f7a47e63511d1f 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -6370,8 +6370,10 @@ void Field::set_guarded_list_length(intptr_t list_length) const {
 
 bool Field::IsUnboxedField() const {
   bool valid_class = (guarded_cid() == kDoubleCid) ||
-                     (FlowGraphCompiler::SupportsUnboxedFloat32x4() &&
-                      (guarded_cid() == kFloat32x4Cid));
+                     (FlowGraphCompiler::SupportsUnboxedSimd128() &&
+                      (guarded_cid() == kFloat32x4Cid)) ||
+                     (FlowGraphCompiler::SupportsUnboxedSimd128() &&
+                      (guarded_cid() == kFloat64x2Cid));
   return is_unboxing_candidate() && !is_final() && !is_nullable() &&
          valid_class;
 }