Don't add borderbox to a path with other arguments.

As borderbox is the default for a clip path, if there are any other
arguments for the clip-path style property, we don't add 'border-box' to
the value.

Bug: 1457596

Change-Id: I83f8d57c63367678266954f30671e67d1a38ae07
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4936936
Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: Yotam Hacohen <yotha@chromium.org>
Auto-Submit: Yotam Hacohen <yotha@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1209594}

third_party/blink/renderer/core/css/properties/longhands/longhands_custom.cc

@@ -1746,7 +1746,11 @@ const CSSValue* ClipPath::ParseSingleValue(CSSParserTokenRange& range,
       list->Append(*basic_shape);
     }
     if (geometry_box) {
-      list->Append(*geometry_box);
+      if (list->length() == 0 ||
+          To<CSSIdentifierValue>(geometry_box)->GetValueID() !=
+              CSSValueID::kBorderBox) {
+        list->Append(*geometry_box);
+      }
     }
     return list;
   }