[promises] Move promise constants to macros.py.

src/js/macros.py

Index: src/js/macros.py
diff --git a/src/js/macros.py b/src/js/macros.py
index 5ad578a2bed959994018ac8a6507b7636cc05075..83d6f4435bf9932fc44970e395b73abf93cf9e7b 100644
--- a/src/js/macros.py
+++ b/src/js/macros.py
@@ -197,3 +197,12 @@ define kArrayInstanceConstructorModified = 28;
 define kLegacyFunctionDeclaration = 29;
 define kRegExpPrototypeSourceGetter = 30;
 define kRegExpPrototypeOldFlagGetter = 31;
+
+# [[PromiseState]] values:
+# These values should be kept in sync with PromiseStatus in globals.h
+define kPending = 0;
+define kFulfilled = 1;
+define kRejected = 2;
+
+define kResolveCallback = 0;
+define kRejectCallback = 1;