Make non-Module generators only context allocate parameters.

test/debugger/debug/es8/async-function-debug-evaluate.js

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// Flags: --noalways-opt
+
 var Debug = debug.Debug;
 var breakPointCount = 0;
 
 function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
   ++breakPointCount;
   try {
     if (breakPointCount === 1) {
       assertEquals(
           "inner", exec_state.frame(0).evaluate("inner").value());
-      assertThrows(() => exec_state.frame(0).evaluate("letInner").value(),
-                   ReferenceError);
-      assertThrows(() => exec_state.frame(0).evaluate("constInner").value(),
-                   ReferenceError);
+      // Variables in TDZ have 'undefined' as their values.
+      assertEquals(undefined, exec_state.frame(0).evaluate("letInner").value());
+      assertEquals(undefined, exec_state.frame(0).evaluate("constInner").value());
 
       assertEquals("outer", exec_state.frame(0).evaluate("outer").value());
       assertEquals(
           "const outer", exec_state.frame(0).evaluate("constOuter").value());
       assertEquals(
           "let outer", exec_state.frame(0).evaluate("letOuter").value());
 
       assertEquals("outer", exec_state.frame(1).evaluate("outer").value());
       assertEquals(
           "const outer", exec_state.frame(1).evaluate("constOuter").value());
       assertEquals(
           "let outer", exec_state.frame(1).evaluate("letOuter").value());
 
-      assertThrows(() => exec_state.frame(0).evaluate("withVar").value(),
-                   ReferenceError);
+      // Variables in TDZ have 'undefined' as their values.
+      assertEquals(undefined, exec_state.frame(0).evaluate("withVar").value());
 
     } else if (breakPointCount === 2) {
       assertEquals(
           "inner", exec_state.frame(0).evaluate("inner").value());
-      assertThrows(() => exec_state.frame(0).evaluate("letInner").value(),
-                   ReferenceError);
-      assertThrows(() => exec_state.frame(0).evaluate("constInner").value(),
-                   ReferenceError);
+      // Variables in TDZ have 'undefined' as their values.
+      assertEquals(undefined, exec_state.frame(0).evaluate("letInner").value());
+      assertEquals(undefined, exec_state.frame(0).evaluate("constInner").value());
 
       assertEquals(57, exec_state.frame(0).evaluate("x").value());
       assertEquals(100, exec_state.frame(0).evaluate("y").value());
 
       // From breakPointCount === 1 and later, it's not possible to access
       // earlier framestates.
       assertEquals("outer", exec_state.frame(0).evaluate("outer").value());
       assertEquals(
           "const outer", exec_state.frame(0).evaluate("constOuter").value());
       assertEquals(
@@ skipping 11 matching lines @@
       assertEquals(
           "const inner", exec_state.frame(0).evaluate("constInner").value());
 
     } else if (breakPointCount === 4) {
       assertEquals(
           "oop", exec_state.frame(0).evaluate("error.message").value());
       assertEquals(
           "Error",
           exec_state.frame(0).evaluate("error.constructor.name").value());
       assertEquals("floof", exec_state.frame(0).evaluate("bun").value());
-      assertThrows(() => exec_state.frame(0).evaluate("cow").value(),
-                   ReferenceError);
+      // Variables in TDZ have 'undefined' as their values.
+      assertEquals(undefined, exec_state.frame(0).evaluate("cow").value())
 
       assertEquals("outer", exec_state.frame(0).evaluate("outer").value());
       assertEquals(
           "const outer", exec_state.frame(0).evaluate("constOuter").value());
       assertEquals(
           "let outer", exec_state.frame(0).evaluate("letOuter").value());
     }
   } catch (e) {
     print(e.stack);
     quit(1);
@@ skipping 43 matching lines @@
 
 test().
 then(x => {
   Debug.setListener(null);
 }).
 catch(error => {
   print(error.stack);
   quit(1);
   Debug.setListener(null);
 });