Bug 857138 - Make Date operate with the boxedValue_unbox proxy trap. r=luke

js/src/jsdate.cpp

@@ -3062,16 +3062,37 @@ js_NewDateObject(JSContext *cx, int year, int mon, int mday,
 }
 
 JS_FRIEND_API(bool)
-js::DateIsValid(JSContext *cx, JSObject *obj)
+js::DateIsValid(JSContext *cx, JSObject *objArg)
 {
-    return obj->is<DateObject>() && !IsNaN(obj->as<DateObject>().UTCTime().toNumber());
+    RootedObject obj(cx, objArg);
+    if (!ObjectClassIs(obj, ESClass_Date, cx))
+        return false;
+
+    RootedValue unboxed(cx);
+    if (!Unbox(cx, obj, &unboxed)) {
+        // This can't actually happen, so we don't force consumers to deal with
+        // a clunky out-param API. Do something sane-ish if it does happen.
+        cx->clearPendingException();
+        return false;
+    }
+
+    return !IsNaN(unboxed.toNumber());
 }
 
 JS_FRIEND_API(double)
-js::DateGetMsecSinceEpoch(JSContext *cx, JSObject *obj)
+js::DateGetMsecSinceEpoch(JSContext *cx, JSObject *objArg)
 {
-    obj = CheckedUnwrap(obj);
-    if (!obj || !obj->is<DateObject>())
+    RootedObject obj(cx, objArg);
+    if (!ObjectClassIs(obj, ESClass_Date, cx))
         return 0;
-    return obj->as<DateObject>().UTCTime().toNumber();
+
+    RootedValue unboxed(cx);
+    if (!Unbox(cx, obj, &unboxed)) {
+        // This can't actually happen, so we don't force consumers to deal with
+        // a clunky out-param API. Do something sane-ish if it does happen.
+        cx->clearPendingException();
+        return 0;
+    }
+
+    return unboxed.toNumber();
 }

js/src/jsobjinlines.h

@@ -801,6 +801,8 @@ Unbox(JSContext *cx, HandleObject obj, MutableHandleValue vp)
         vp.setNumber(obj->as<NumberObject>().unbox());
     else if (obj->is<StringObject>())
         vp.setString(obj->as<StringObject>().unbox());
+    else if (obj->is<DateObject>())
+        vp.set(obj->as<DateObject>().UTCTime());
     else
         vp.setUndefined();
 

js/src/vm/StructuredClone.cpp

@@ -1060,8 +1060,10 @@ JSStructuredCloneWriter::startWrite(HandleValue v)
             return out.writePair(SCTAG_REGEXP_OBJECT, re->getFlags()) &&
                    writeString(SCTAG_STRING, re->getSource());
         } else if (ObjectClassIs(obj, ESClass_Date, context())) {
-            double d = DateGetMsecSinceEpoch(context(), obj);
-            return out.writePair(SCTAG_DATE_OBJECT, 0) && out.writeDouble(d);
+            RootedValue unboxed(context());
+            if (!Unbox(context(), obj, &unboxed))
+                return false;
+            return out.writePair(SCTAG_DATE_OBJECT, 0) && out.writeDouble(unboxed.toNumber());
         } else if (JS_IsTypedArrayObject(obj)) {
             return writeTypedArray(obj);
         } else if (JS_IsArrayBufferObject(obj) && JS_ArrayBufferHasData(obj)) {