Reapply "Shuffle around deopt id allocation...

runtime/vm/regexp_assembler_ir.h

Index: runtime/vm/regexp_assembler_ir.h
diff --git a/runtime/vm/regexp_assembler_ir.h b/runtime/vm/regexp_assembler_ir.h
index ae70952201228d93b58490981a5560ef6c489f00..8dbb4abe99251661fa058fe818ad2fd3be49ffc9 100644
--- a/runtime/vm/regexp_assembler_ir.h
+++ b/runtime/vm/regexp_assembler_ir.h
@@ -132,6 +132,8 @@ class IRRegExpMacroAssembler : public RegExpMacroAssembler {
   void FinalizeRegistersArray();
 
  private:
+  intptr_t GetNextDeoptId() const { return thread_->GetNextDeoptId(); }
+
   // Generate the contents of preset blocks. The entry block is the entry point
   // of the generated code.
   void GenerateEntryBlock();
@@ -359,6 +361,8 @@ class IRRegExpMacroAssembler : public RegExpMacroAssembler {
     intptr_t next_id;
   };
 
+  Thread* thread_;
+
   // Which mode to generate code for (ASCII or UC16).
   Mode mode_;