Bug 1300071 - Create an API to access DOM Promise's state. r=bz

MozReview-Commit-ID: LI2Dafkzq5x

--HG--
extra : transplant_source : %DA%0D%EC%0B%8A%AD%80A%CC%17%D2%E6%9F%90%A2%9E%92%1E%26%1A

dom/promise/Promise.cpp

@@ -3246,5 +3246,30 @@ Promise::GetID() {
 }
 #endif // SPIDERMONKEY_PROMISE
 
+#ifndef SPIDERMONKEY_PROMISE
+Promise::PromiseState
+Promise::State() const
+{
+  return mState;
+}
+#else // SPIDERMONKEY_PROMISE
+Promise::PromiseState
+Promise::State() const
+{
+  JS::Rooted<JSObject*> p(RootingCx(), PromiseObj());
+  const JS::PromiseState state = JS::GetPromiseState(p);
+
+  if (state == JS::PromiseState::Fulfilled) {
+      return PromiseState::Resolved;
+  }
+
+  if (state == JS::PromiseState::Rejected) {
+      return PromiseState::Rejected;
+  }
+
+  return PromiseState::Pending;
+}
+#endif // SPIDERMONKEY_PROMISE
+
 } // namespace dom
 } // namespace mozilla

dom/promise/Promise.h

@@ -313,6 +313,14 @@ public:
                      JS::Handle<JSObject*> aPromiseObj);
 #endif // SPIDERMONKEY_PROMISE
 
+  enum class PromiseState {
+    Pending,
+    Resolved,
+    Rejected
+  };
+
+  PromiseState State() const;
+
 protected:
   struct PromiseCapability;
 
@@ -369,12 +377,6 @@ protected:
 #endif // SPIDERMONKEY_PROMISE
 
 private:
-  enum PromiseState {
-    Pending,
-    Resolved,
-    Rejected
-  };
-
 #ifndef SPIDERMONKEY_PROMISE
   friend class PromiseDebugging;