allow timeZone to be specified as an intl option

Author: icambron

src/impl/locale.js

@@ -186,7 +186,7 @@ class PolyDateFormatter {
   constructor(dt, intl, opts) {
     this.opts = opts;
 
-    let z;
+    let z = undefined;
     if (dt.zone.isUniversal) {
       // UTC-8 or Etc/UTC-8 are not part of tzdata, only Etc/GMT+8 and the like.
       // That is why fixed-offset TZ is set to that unless it is:
@@ -222,9 +222,7 @@ class PolyDateFormatter {
     }
 
     const intlOpts = { ...this.opts };
-    if (z) {
-      intlOpts.timeZone = z;
-    }
+    intlOpts.timeZone = intlOpts.timeZone || z;
     this.dtf = getCachedDTF(intl, intlOpts);
   }
 

test/datetime/format.test.js

@@ -415,10 +415,20 @@ test("DateTime#toLocaleString uses locale-appropriate time formats", () => {
   expect(dt.reconfigure({ locale: "es" }).toLocaleString(DateTime.TIME_24_SIMPLE)).toBe("9:23");
 });
 
+test("DateTime#toLocaleString() accepts a zone even when the zone is set", () => {
+  expect(
+    dt.toLocaleString({
+      hour: "numeric",
+      minute: "numeric",
+      timeZoneName: "short",
+      timeZone: "America/Los_Angeles",
+    })
+  ).toBe("2:23 AM PDT");
+});
+
 //------
 // #resolvedLocaleOpts()
 //------
-
 test("DateTime#resolvedLocaleOpts returns a thing", () => {
   const res = DateTime.now().resolvedLocaleOptions();