Fix evaluating in async/sync*/async* methods.

runtime/vm/debugger.cc

Index: runtime/vm/debugger.cc
diff --git a/runtime/vm/debugger.cc b/runtime/vm/debugger.cc
index 155512ad4fd4b1c7e5e849f3baa3cfaaa4033002..e485255ff6b6c4f6110c74b2f97e335ab8438946 100644
--- a/runtime/vm/debugger.cc
+++ b/runtime/vm/debugger.cc
@@ -972,7 +972,12 @@ RawObject* ActivationFrame::GetReceiver() {
 }
 
 
-bool IsPrivateVariableName(const String& var_name) {
+static bool IsSyntheticVariableName(const String& var_name) {
+  return (var_name.Length() >= 1) && (var_name.CharAt(0) == ':');
+}
+
+
+static bool IsPrivateVariableName(const String& var_name) {
   return (var_name.Length() >= 1) && (var_name.CharAt(0) == '_');
 }
 
@@ -989,7 +994,7 @@ RawObject* ActivationFrame::Evaluate(const String& expr) {
   for (intptr_t i = 0; i < num_variables; i++) {
     TokenPosition ignore;
     VariableAt(i, &name, &ignore, &ignore, &value);
-    if (!name.Equals(Symbols::This())) {
+    if (!name.Equals(Symbols::This()) && !IsSyntheticVariableName(name)) {
       if (IsPrivateVariableName(name)) {
         name = String::ScrubName(name);
       }