Bug 1781205: Move Await of AsyncGeneratorYield. r=arai

Spec PR: tc39/ecma262#2819

The PR moves the `Await` operation of out `AsyncGeneratorYield` and instead
executes it before calling `AsyncGeneratorYield` from `Yield`.

`BytecodeEmitter::emitYieldStar()` has an inlined implementation of the
`AsyncGeneratorYield` operation. Removing the call to `emitAwaitInInnermostScope()`
is equivalent to removing the `Await` operation in `AsyncGeneratorYield`.

And in `BytecodeEmitter::emitYield()` we only need to remove the comment
explaining why we call `emitAwaitInInnermostScope()`, because executing `Await`
is now part of the normal evaluation of the `Yield` expression and no longer
happens in `AsyncGeneratorYield`.

Differential Revision: https://phabricator.services.mozilla.com/D156933

js/src/frontend/BytecodeEmitter.cpp

@@ -6174,7 +6174,6 @@ bool BytecodeEmitter::emitYield(UnaryNode* yieldNode) {
     }
   }
 
-  // 25.5.3.7 AsyncGeneratorYield step 5.
   if (sc->asSuspendableContext()->isAsync()) {
     MOZ_ASSERT(!needsIteratorResult);
     if (!emitAwaitInInnermostScope()) {
@@ -6720,10 +6719,6 @@ bool BytecodeEmitter::emitYieldStar(ParseNode* iter) {
       //            [stack] NEXT ITER RESULT
       return false;
     }
-    if (!emitAwaitInInnermostScope()) {
-      //            [stack] NEXT ITER RESULT
-      return false;
-    }
   }
   if (!emitGetDotGeneratorInInnermostScope()) {
     //              [stack] NEXT ITER RESULT GENOBJ

js/src/tests/jstests.list

@@ -609,10 +609,6 @@ skip script test262/built-ins/AsyncGeneratorPrototype/return/return-state-comple
 skip script test262/built-ins/AsyncGeneratorPrototype/return/return-suspendedStart-broken-promise.js
 skip script test262/built-ins/AsyncGeneratorPrototype/return/return-suspendedYield-broken-promise-try-catch.js
 
-# https://bugzilla.mozilla.org/show_bug.cgi?id=1781205
-skip script test262/language/statements/async-generator/yield-star-return-then-getter-ticks.js
-skip script test262/language/statements/async-generator/yield-star-promise-not-unwrapped.js
-
 # https://github.com/tc39/proposal-intl-numberformat-v3/pull/107
 skip script test262/intl402/NumberFormat/test-option-useGrouping.js