Normative: add Promise.try (#3327)

See tc39/proposal-promise-try#15

Author: ljharb

spec.html

@@ -47588,6 +47588,25 @@ <h1>
         </emu-clause>
       </emu-clause>
 
+      <emu-clause id="sec-promise.try">
+        <h1>Promise.try ( _callback_, ..._args_ )</h1>
+        <p>When the `try` method is called with argument _callback_, the following steps are taken:</p>
+        <emu-alg>
+          1. Let _C_ be the *this* value.
+          1. If _C_ is not an Object, throw a *TypeError* exception.
+          1. Let _promiseCapability_ be ? NewPromiseCapability(_C_).
+          1. Let _status_ be Completion(Call(_callback_, *undefined*, _args_)).
+          1. If _status_ is an abrupt completion, then
+            1. Perform ? Call(_promiseCapability_.[[Reject]], *undefined*, « _status_.[[Value]] »).
+          1. Else,
+            1. Perform ? Call(_promiseCapability_.[[Resolve]], *undefined*, « _status_.[[Value]] »).
+          1. Return _promiseCapability_.[[Promise]].
+        </emu-alg>
+        <emu-note>
+          <p>This function expects its *this* value to be a constructor function that supports the parameter conventions of the Promise constructor.</p>
+        </emu-note>
+      </emu-clause>
+
       <emu-clause id="sec-promise.withResolvers">
         <h1>Promise.withResolvers ( )</h1>
         <p>This function returns an object with three properties: a new promise together with the `resolve` and `reject` functions associated with it.</p>