Enable PreloadImageSrcSet feature by default

This enables imagesrcset and imagesizes attributes on <link>.

Intent to Ship:
https://groups.google.com/a/chromium.org/d/msg/blink-dev/07CbItWfA4M/CG1qF8IoEAAJ

Bug: 813452
Change-Id: I9396fe35729069ef56b461aa99cf85e9b1e51302
Reviewed-on: https://chromium-review.googlesource.com/c/1414513
Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Kunihiko Sakamoto <ksakamoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#623170}
diff --git a/third_party/blink/renderer/platform/runtime_enabled_features.json5 b/third_party/blink/renderer/platform/runtime_enabled_features.json5
index dc1ffd3..cf76224c 100644
--- a/third_party/blink/renderer/platform/runtime_enabled_features.json5
+++ b/third_party/blink/renderer/platform/runtime_enabled_features.json5
@@ -1039,7 +1039,7 @@
     },
     {
       name: "PreloadImageSrcSet",
-      status: "experimental",
+      status: "stable",
     },
     {
       name: "Presentation",
diff --git a/third_party/blink/web_tests/virtual/stable/webexposed/element-instance-property-listing-expected.txt b/third_party/blink/web_tests/virtual/stable/webexposed/element-instance-property-listing-expected.txt
index 76c19c2..2dc7b5e 100644
--- a/third_party/blink/web_tests/virtual/stable/webexposed/element-instance-property-listing-expected.txt
+++ b/third_party/blink/web_tests/virtual/stable/webexposed/element-instance-property-listing-expected.txt
@@ -687,6 +687,8 @@
     property disabled
     property href
     property hreflang
+    property imageSizes
+    property imageSrcset
     property import
     property integrity
     property media
diff --git a/third_party/blink/web_tests/virtual/stable/webexposed/global-interface-listing-expected.txt b/third_party/blink/web_tests/virtual/stable/webexposed/global-interface-listing-expected.txt
index 2a1cbcb..193e823 100644
--- a/third_party/blink/web_tests/virtual/stable/webexposed/global-interface-listing-expected.txt
+++ b/third_party/blink/web_tests/virtual/stable/webexposed/global-interface-listing-expected.txt
@@ -2667,6 +2667,8 @@
     getter disabled
     getter href
     getter hreflang
+    getter imageSizes
+    getter imageSrcset
     getter import
     getter integrity
     getter media
@@ -2685,6 +2687,8 @@
     setter disabled
     setter href
     setter hreflang
+    setter imageSizes
+    setter imageSrcset
     setter integrity
     setter media
     setter referrerPolicy