letter-spacing: add percentages subfeature (#29200)

* Chrome 145 letter-spacing and word-spacing percentage support

* Update css/properties/letter-spacing.json

Co-authored-by: Claas Augner <495429+caugner@users.noreply.github.com>

* Update spec_url

* Update spec_url

---------

Co-authored-by: Claas Augner <495429+caugner@users.noreply.github.com>

Author: chrisdavidmills

css/properties/letter-spacing.json

@@ -86,6 +86,38 @@
             }
           }
         },
+        "percentages": {
+          "__compat": {
+            "description": "`<percentage>` values",
+            "spec_url": "https://www.w3.org/TR/css-text-4/#valdef-letter-spacing-length-percentage",
+            "support": {
+              "chrome": {
+                "version_added": "145"
+              },
+              "chrome_android": "mirror",
+              "edge": "mirror",
+              "firefox": {
+                "version_added": "45"
+              },
+              "firefox_android": "mirror",
+              "oculus": "mirror",
+              "opera": "mirror",
+              "opera_android": "mirror",
+              "safari": {
+                "version_added": "7"
+              },
+              "safari_ios": "mirror",
+              "samsunginternet_android": "mirror",
+              "webview_android": "mirror",
+              "webview_ios": "mirror"
+            },
+            "status": {
+              "experimental": false,
+              "standard_track": true,
+              "deprecated": false
+            }
+          }
+        },
         "svg_elements": {
           "__compat": {
             "description": "On SVG elements",

css/properties/word-spacing.json

@@ -89,6 +89,7 @@
         "percentages": {
           "__compat": {
             "description": "`<percentage>` values",
+            "spec_url": "https://www.w3.org/TR/css-text-4/#valdef-word-spacing-length-percentage",
             "support": {
               "chrome": {
                 "version_added": "145"
@@ -112,8 +113,8 @@
             },
             "status": {
               "experimental": false,
-              "standard_track": false,
-              "deprecated": true
+              "standard_track": true,
+              "deprecated": false
             }
           }
         },