Track the 'awaiter return' call stack use it to detect uncaught exceptions in async functions

runtime/vm/intermediate_language.h

Index: runtime/vm/intermediate_language.h
diff --git a/runtime/vm/intermediate_language.h b/runtime/vm/intermediate_language.h
index 54501a4f1d3d17e024e4e8a149fd4bc076ec8cdd..1e55083b28f8a4fda9cf0abe9511ca0446cc538a 100644
--- a/runtime/vm/intermediate_language.h
+++ b/runtime/vm/intermediate_language.h
@@ -1469,7 +1469,9 @@ class IndirectEntryInstr : public JoinEntryInstr {
 
 class CatchBlockEntryInstr : public BlockEntryInstr {
  public:
-  CatchBlockEntryInstr(intptr_t block_id,
+  CatchBlockEntryInstr(TokenPosition handler_token_pos,
+                       bool is_generated,
+                       intptr_t block_id,
                        intptr_t try_index,
                        GraphEntryInstr* graph_entry,
                        const Array& handler_types,
@@ -1487,7 +1489,9 @@ class CatchBlockEntryInstr : public BlockEntryInstr {
         exception_var_(exception_var),
         stacktrace_var_(stacktrace_var),
         needs_stacktrace_(needs_stacktrace),
-        should_restore_closure_context_(should_restore_closure_context) {
+        should_restore_closure_context_(should_restore_closure_context),
+        handler_token_pos_(handler_token_pos),
+        is_generated_(is_generated) {
     deopt_id_ = deopt_id;
   }
 
@@ -1508,6 +1512,9 @@ class CatchBlockEntryInstr : public BlockEntryInstr {
 
   bool needs_stacktrace() const { return needs_stacktrace_; }
 
+  bool is_generated() const { return is_generated_; }
+  TokenPosition handler_token_pos() const { return handler_token_pos_; }
+
   // Returns try index for the try block to which this catch handler
   // corresponds.
   intptr_t catch_try_index() const { return catch_try_index_; }
@@ -1541,6 +1548,8 @@ class CatchBlockEntryInstr : public BlockEntryInstr {
   const LocalVariable& stacktrace_var_;
   const bool needs_stacktrace_;
   const bool should_restore_closure_context_;
+  TokenPosition handler_token_pos_;
+  bool is_generated_;
 
   DISALLOW_COPY_AND_ASSIGN(CatchBlockEntryInstr);
 };