Revert "Track the 'awaiter return' call stack..."

runtime/vm/compiler.cc

Index: runtime/vm/compiler.cc
diff --git a/runtime/vm/compiler.cc b/runtime/vm/compiler.cc
index 5a621efd5ce2e60f4b47a62f1662480e085f7eb9..2a109dbe322a2cc461fc2ad07afbf13813ed1163 100644
--- a/runtime/vm/compiler.cc
+++ b/runtime/vm/compiler.cc
@@ -543,34 +543,6 @@ void CompileParsedFunctionHelper::FinalizeCompilation(
       Code::Handle(Code::FinalizeCode(function, assembler, optimized()));
   code.set_is_optimized(optimized());
   code.set_owner(function);
-#if !defined(PRODUCT)
-  if (FLAG_support_debugger) {
-    ZoneGrowableArray<TokenPosition>* await_token_positions =
-        flow_graph->await_token_positions();
-    if (await_token_positions != NULL) {
-      Smi& token_pos_value = Smi::Handle(zone);
-      if (await_token_positions->length() > 0) {
-        const Array& await_to_token_map = Array::Handle(
-            zone, Array::New(await_token_positions->length(), Heap::kOld));
-        ASSERT(!await_to_token_map.IsNull());
-        for (intptr_t i = 0; i < await_token_positions->length(); i++) {
-          TokenPosition token_pos =
-              await_token_positions->At(i).FromSynthetic();
-          if (!token_pos.IsReal()) {
-            // Some async machinary uses sentinel values. Map them to
-            // no source position.
-            token_pos_value = Smi::New(TokenPosition::kNoSourcePos);
-          } else {
-            token_pos_value = Smi::New(token_pos.value());
-          }
-          await_to_token_map.SetAt(i, token_pos_value);
-        }
-        code.SetAwaitTokenPositions(await_to_token_map);
-      }
-    }
-  }
-#endif  // !defined(PRODUCT)
-
   if (!function.IsOptimizable()) {
     // A function with huge unoptimized code can become non-optimizable
     // after generating unoptimized code.