[roll third_party/pigweed] pw_web: Replace Map() with object in proto collection

In some bundling configs `new Map()` is not supported.
We can just use standard object instead.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/170493

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: f210a064bf6d67f..df46ed322724b8a
Roller-URL: https://ci.chromium.org/b/8770138936485561185
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Icb270ee708bec80ca945e2dc5f09e162d34aef89
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/170630
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index f210a06..df46ed3 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit f210a064bf6d67fe0d58074f4e3a6eed1e9851bd
+Subproject commit df46ed322724b8aac0c610cd3ed5c75d68fbdce1