Revert "Improvements to causal async stack traces"

runtime/vm/debugger.cc

Index: runtime/vm/debugger.cc
diff --git a/runtime/vm/debugger.cc b/runtime/vm/debugger.cc
index 0c0edcc769aa9480232142a1447d2ae444b78668..e234b84c7ac3c5d43de446db7b9e1c50831430eb 100644
--- a/runtime/vm/debugger.cc
+++ b/runtime/vm/debugger.cc
@@ -1702,10 +1702,6 @@ DebuggerStackTrace* Debugger::CollectAsyncCausalStackTrace() {
       if (async_stack_trace.CodeAtFrame(i) ==
           StubCode::AsynchronousGapMarker_entry()->code()) {
         stack_trace->AddMarker(ActivationFrame::kAsyncSuspensionMarker);
-        // The frame immediately below the asynchronous gap marker is the
-        // identical to the frame above the marker. Skip the frame to enhance
-        // the readability of the trace.
-        i++;
       } else {
         code = Code::RawCast(async_stack_trace.CodeAtFrame(i));
         offset = Smi::RawCast(async_stack_trace.PcOffsetAtFrame(i));