Move deopt_id and related helpers/definitions from Isolate to Thread

runtime/vm/code_descriptors.cc

Index: runtime/vm/code_descriptors.cc
diff --git a/runtime/vm/code_descriptors.cc b/runtime/vm/code_descriptors.cc
index 5a9ba10eb888e0b14f513c64d19054e983a7855e..adc78537f6630d148a74ff0fb6d6635f1ab89222 100644
--- a/runtime/vm/code_descriptors.cc
+++ b/runtime/vm/code_descriptors.cc
@@ -13,7 +13,7 @@ void DescriptorList::AddDescriptor(RawPcDescriptors::Kind kind,
                                    intptr_t try_index) {
   ASSERT((kind == RawPcDescriptors::kRuntimeCall) ||
          (kind == RawPcDescriptors::kOther) ||
-         (deopt_id != Isolate::kNoDeoptId));
+         (deopt_id != Thread::kNoDeoptId));
 
   intptr_t merged_kind_try =
       RawPcDescriptors::MergedKindTry::Encode(kind, try_index);