Use DecodeURLMode::kUTF8 for URLSearchParams

According to the URL specification, the URLSearchParams should use the
default "replacement" error mode for decoding URL escape sequences.

Change-Id: I69007a40dffc3516a448549b9329e106bdf39227
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1669297
Commit-Queue: Eero Häkkinen <eero.hakkinen@intel.com>
Reviewed-by: Hiroshige Hayashizaki <hiroshige@chromium.org>
Reviewed-by: Mike West <mkwst@chromium.org>
Cr-Commit-Position: refs/heads/master@{#674915}
4 files changed