[async-await] (simpler) fix for Return in try/finally in async functions

src/ast/scopes.h

Index: src/ast/scopes.h
diff --git a/src/ast/scopes.h b/src/ast/scopes.h
index ea37890c5e4875406996b0a5916141fc2459fc82..d5e9326f16a12750b8268752b882ec6e9f9c7f32 100644
--- a/src/ast/scopes.h
+++ b/src/ast/scopes.h
@@ -680,6 +680,11 @@ class DeclarationScope : public Scope {
   // calls sloppy eval.
   Variable* DeclareFunctionVar(const AstRawString* name);
 
+  // Declare some special internal variables which must be accessible to
+  // Ignition without ScopeInfo.
+  Variable* DeclareGeneratorObjectVar(const AstRawString* name);
+  Variable* DeclarePromiseVar(const AstRawString* name);
+
   // Declare a parameter in this scope.  When there are duplicated
   // parameters the rightmost one 'wins'.  However, the implementation
   // expects all parameters to be declared and from left to right.
@@ -718,6 +723,17 @@ class DeclarationScope : public Scope {
     return function_;
   }
 
+  Variable* generator_object_var() const {
+    DCHECK(is_function_scope() || is_module_scope());
+    return generator_object_;
+  }
+
+  Variable* promise_var() const {
+    DCHECK(is_function_scope());
+    DCHECK(IsAsyncFunction(function_kind_));
+    return promise_;
+  }
+
   // Parameters. The left-most parameter has index 0.
   // Only valid for function and module scopes.
   Variable* parameter(int index) const {
@@ -874,6 +890,11 @@ class DeclarationScope : public Scope {
   Variable* arguments_;
   // Convenience variable; Subclass constructor only
   Variable* this_function_;
+
+  // Generator object, if any; generator function scopes and module scopes only.
+  Variable* generator_object_;
+  // Promise, if any; async function scopes only.
+  Variable* promise_;

[Dan Ehrenberg, 2017/02/08 21:12:56]

Will there be more live DeclarationScopes than FunctionStates at a time? If so,
moving the variables this way this might cause a (probably minor) increase in
memory usage.

 };
 
 class ModuleScope final : public DeclarationScope {