CSS Conic Gradients: do not support unitless 0 angles

third_party/WebKit/LayoutTests/fast/css/usecounter-angle-zero-gradient.html

Index: third_party/WebKit/LayoutTests/fast/css/usecounter-angle-zero-gradient.html
diff --git a/third_party/WebKit/LayoutTests/fast/css/usecounter-angle-zero-gradient.html b/third_party/WebKit/LayoutTests/fast/css/usecounter-angle-zero-gradient.html
index 106288bfaa36f7a97a8517d8571cae01514f19ed..4036ead4d6f00e6a620bc931ad6ecc68c841d9d5 100644
--- a/third_party/WebKit/LayoutTests/fast/css/usecounter-angle-zero-gradient.html
+++ b/third_party/WebKit/LayoutTests/fast/css/usecounter-angle-zero-gradient.html
@@ -14,6 +14,9 @@ test(() => {
     div.style = 'image-orientation: 0;';
     div.style = 'rotate: 0;';
     div.style = 'offset-path: ray(0 closest-side);';
+    div.style = 'background-image: conic-gradient(from 0 at left top, red 0deg, green 180deg);';
+    div.style = 'background-image: conic-gradient(from 0deg at left top, red 0, green 180deg);';
+
     // These properties have their own counters.
     div.style = 'filter: hue-rotate(0);';
     div.style = 'offset-rotate: 0;';
@@ -28,5 +31,5 @@ test(() => {
     div.style = 'background-image: linear-gradient(0, red, black);';
     assert_true(isCounted(),
                 '0 should be counted');
-}, 'angle 0 is use counted for gradient');
+}, 'angle 0 is use counted for linear gradient');
 </script>