DEPS: update libwebp to v1.1.0-28-g55a080e5
DEPS: update libwebp to v1.1.0-28-g55a080e5

picks up a couple ubsan fixes

24 commits:
https://chromium.googlesource.com/webm/libwebp/+log/0fa56f3..55a080

Bug: skia:10693
Change-Id: I2ffa72d1e60b2034bd01eb11ede39bf70726fbe7
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/316379
Commit-Queue: Leon Scroggins <995cad867ca30d6399abe011583a53547c8afea1@google.com>
Reviewed-by: Leon Scroggins <995cad867ca30d6399abe011583a53547c8afea1@google.com>

google/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,google/skia,google/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,google/skia,google/skia