Don't use a special var descriptor for :async_op since it can now be either stack or context alloca…

runtime/vm/scopes.cc

Index: runtime/vm/scopes.cc
diff --git a/runtime/vm/scopes.cc b/runtime/vm/scopes.cc
index 139705a0079817463415683fd9f7b4dcf19c348e..0881b8725ec851b723d6724bf9e3824a51c00deb 100644
--- a/runtime/vm/scopes.cc
+++ b/runtime/vm/scopes.cc
@@ -250,8 +250,12 @@ int LocalScope::AllocateVariables(int first_parameter_index,
 
 
 // The parser creates internal variables that start with ":"
-static bool IsInternalIdentifier(const String& str) {
+static bool IsFilteredIdentifier(const String& str) {
   ASSERT(str.Length() > 0);
+  if (str.raw() == Symbols::AsyncOperation().raw()) {
+    // Keep :async_op for asynchronous debugging.
+    return false;
+  }
   return str.CharAt(0) == ':';
 }
 
@@ -266,10 +270,8 @@ RawLocalVarDescriptors* LocalScope::GetVarDescriptors(const Function& func) {
     for (int i = 0; i < context_scope.num_variables(); i++) {
       String& name = String::Handle(context_scope.NameAt(i));
       RawLocalVarDescriptors::VarInfoKind kind;
-      if (!IsInternalIdentifier(name)) {
+      if (!IsFilteredIdentifier(name)) {
         kind = RawLocalVarDescriptors::kContextVar;
-      } else if (name.raw() == Symbols::AsyncOperation().raw()) {
-        kind = RawLocalVarDescriptors::kAsyncOperation;
       } else {
         continue;
       }
@@ -319,24 +321,7 @@ void LocalScope::CollectLocalVariables(GrowableArray<VarDesc>* vars,
   for (int i = 0; i < this->variables_.length(); i++) {
     LocalVariable* var = variables_[i];
     if ((var->owner() == this) && !var->is_invisible()) {
-      if (!IsInternalIdentifier(var->name())) {
-        // This is a regular Dart variable, either stack-based or captured.
-        VarDesc desc;
-        desc.name = &var->name();
-        if (var->is_captured()) {
-          desc.info.set_kind(RawLocalVarDescriptors::kContextVar);
-          ASSERT(var->owner() != NULL);
-          ASSERT(var->owner()->context_level() >= 0);
-          desc.info.scope_id = var->owner()->context_level();
-        } else {
-          desc.info.set_kind(RawLocalVarDescriptors::kStackVar);
-          desc.info.scope_id = *scope_id;
-        }
-        desc.info.begin_pos = var->token_pos();
-        desc.info.end_pos = var->owner()->end_token_pos();
-        desc.info.set_index(var->index());
-        vars->Add(desc);
-      } else if (var->name().raw() == Symbols::CurrentContextVar().raw()) {
+      if (var->name().raw() == Symbols::CurrentContextVar().raw()) {
         // This is the local variable in which the function saves its
         // own context before calling a closure function.
         VarDesc desc;
@@ -347,21 +332,21 @@ void LocalScope::CollectLocalVariables(GrowableArray<VarDesc>* vars,
         desc.info.end_pos = 0;
         desc.info.set_index(var->index());
         vars->Add(desc);
-      } else if (var->name().raw() == Symbols::AsyncOperation().raw()) {
-        // The async continuation.
-        ASSERT(var->is_captured());
+      } else if (!IsFilteredIdentifier(var->name())) {
+        // This is a regular Dart variable, either stack-based or captured.
         VarDesc desc;
         desc.name = &var->name();
-        desc.info.set_kind(RawLocalVarDescriptors::kAsyncOperation);
         if (var->is_captured()) {
+          desc.info.set_kind(RawLocalVarDescriptors::kContextVar);
           ASSERT(var->owner() != NULL);
           ASSERT(var->owner()->context_level() >= 0);
           desc.info.scope_id = var->owner()->context_level();
         } else {
+          desc.info.set_kind(RawLocalVarDescriptors::kStackVar);
           desc.info.scope_id = *scope_id;
         }
-        desc.info.begin_pos = 0;
-        desc.info.end_pos = 0;
+        desc.info.begin_pos = var->token_pos();
+        desc.info.end_pos = var->owner()->end_token_pos();
         desc.info.set_index(var->index());
         vars->Add(desc);
       }