feat(css): Add missing rect() and xywh() functions (#927)

Author: skyclouds2001

css/functions.json

@@ -516,6 +516,14 @@
     "status": "standard",
     "mdn_url": "https://developer.mozilla.org/docs/Web/CSS/ray"
   },
+  "rect()": {
+    "syntax": "rect( [ <length-percentage> | auto ]{4} [ round <'border-radius'> ]? )",
+    "groups": [
+      "CSS Shapes"
+    ],
+    "status": "standard",
+    "mdn_url": "https://developer.mozilla.org/docs/Web/CSS/basic-shape/rect"
+  },
   "rem()": {
     "syntax": "rem( <calc-sum>, <calc-sum> )",
     "groups": [
@@ -825,5 +833,13 @@
     ],
     "status": "experimental",
     "mdn_url": "https://developer.mozilla.org/docs/Web/CSS/animation-timeline/view"
+  },
+  "xywh()": {
+    "syntax": "xywh( <length-percentage>{2} <length-percentage [0,∞]>{2} [ round <'border-radius'> ]? )",
+    "groups": [
+      "CSS Shapes"
+    ],
+    "status": "standard",
+    "mdn_url": "https://developer.mozilla.org/docs/Web/CSS/basic-shape/xywh"
   }
 }

css/syntaxes.json

@@ -752,6 +752,9 @@
   "relative-size": {
     "syntax": "larger | smaller"
   },
+  "rect()": {
+    "syntax": "rect( [ <length-percentage> | auto ]{4} [ round <'border-radius'> ]? )"
+  },
   "rem()": {
     "syntax": "rem( <calc-sum>, <calc-sum> )"
   },
@@ -1031,6 +1034,9 @@
   "wq-name": {
     "syntax": "<ns-prefix>? <ident-token>"
   },
+  "xywh()": {
+    "syntax": "xywh( <length-percentage>{2} <length-percentage [0,∞]>{2} [ round <'border-radius'> ]? )"
+  },
   "xyz": {
     "syntax": "xyz | xyz-d50 | xyz-d65"
   },