Reapply "Use CodeSourceMap for stack traces (still JIT only)."

runtime/vm/exceptions.cc

Index: runtime/vm/exceptions.cc
diff --git a/runtime/vm/exceptions.cc b/runtime/vm/exceptions.cc
index bc0bd111aee300701ac2704b7fdd3c3213c8f448..8da9f575110856c39b778fa7034730b6f17c318a 100644
--- a/runtime/vm/exceptions.cc
+++ b/runtime/vm/exceptions.cc
@@ -98,7 +98,7 @@ void PreallocatedStackTraceBuilder::AddFrame(const Code& code,
     dropped_frames_++;
     // Add an empty slot to indicate the overflow so that the toString
     // method can account for the overflow.
-    if (stacktrace_.FunctionAtFrame(null_slot) != Function::null()) {
+    if (stacktrace_.CodeAtFrame(null_slot) != Code::null()) {
       stacktrace_.SetCodeAtFrame(null_slot, frame_code);
       // We drop an extra frame here too.
       dropped_frames_++;