Reland “Enable property-no-vendor-prefix stylelint check”

This patch drops unnecessary -webkit- prefixes in CSS and enables
a lint check to enforce that prevent such properties from being
added in the future. Note that the use of vendor-prefixed CSS
properties is still accepted in cases where there is no standardized
and browser-supported alternative.

[email protected]

No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:1104187
Change-Id: Ibf36fe5a3802b5f3ac663b7ac873a4758e0fda14
Fixed: chromium:1031475
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2297386
Reviewed-by: Changhao Han <[email protected]>
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2297393
Commit-Queue: Mathias Bynens <[email protected]>
Auto-Submit: Mathias Bynens <[email protected]>
Reviewed-by: Mathias Bynens <[email protected]>
diff --git a/front_end/ui/treeoutline.css b/front_end/ui/treeoutline.css
index 1a159c0..7d938ed 100644
--- a/front_end/ui/treeoutline.css
+++ b/front_end/ui/treeoutline.css
@@ -113,7 +113,7 @@
   -webkit-mask-size: 32px 24px;
   -webkit-mask-position: 0 0;
   background-color: #727272;
-  content: "\00a0\00a0";
+  content: "\A0\A0";
   text-shadow: none;
   margin-right: -2px;
   height: 12px;