Fix predefined color space undefined jsrepr

Small fix found during emscripten updates.

Bug: none
Change-Id: Ib678a2002c76c0f7fd7bea5431a36df501c22074
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/80700
Commit-Queue: Shrek Shao <shrekshao@google.com>
Auto-Submit: Shrek Shao <shrekshao@google.com>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>
diff --git a/dawn.json b/dawn.json
index bc757a2..eeb5d7c 100644
--- a/dawn.json
+++ b/dawn.json
@@ -1526,7 +1526,7 @@
     "predefined color space": {
         "category": "enum",
         "values": [
-            {"value": 0, "name": "undefined"},
+            {"value": 0, "name": "undefined", "jsrepr": "undefined"},
             {"value": 1, "name": "srgb"}
         ]
     },