Bug 1869738. Add a test for transformed stroked lines. r=lsalzman

Differential Revision: https://phabricator.services.mozilla.com/D196350

layout/reftests/canvas/reftest.list

@@ -125,3 +125,5 @@ fuzzy-if(winWidget,0-94,0-1575) fuzzy-if(cocoaWidget,0-1,0-34) == 1304353-text-g
 == 1850284-1.html 1850284-1-ref.html
 
 != 1850727-1.html 1850727-1-ref.html
+
+== transformed-line-stroke.html transformed-line-stroke-ref.html

layout/reftests/canvas/transformed-line-stroke-ref.html

@@ -0,0 +1,15 @@
+<canvas id=c></canvas>
+<script>
+const canvas = document.getElementById("c");
+const ctx = canvas.getContext("2d");
+
+canvas.width = 600;
+canvas.height = 300;
+
+
+ctx.strokeStyle = "rgba(0, 0, 0, 1)";
+ctx.beginPath();
+ctx.moveTo(87, 137.5);
+ctx.lineTo(738, 137.5);
+ctx.stroke();
+</script>

layout/reftests/canvas/transformed-line-stroke.html

@@ -0,0 +1,16 @@
+<canvas id=c></canvas>
+<script>
+const canvas = document.getElementById("c");
+const ctx = canvas.getContext("2d");
+
+canvas.width = 600;
+canvas.height = 300;
+
+ctx.translate(-5, 0);
+
+ctx.strokeStyle = "rgba(0, 0, 0, 1)";
+ctx.beginPath();
+ctx.moveTo(93, 137.5);
+ctx.lineTo(741, 137.5);
+ctx.stroke();
+</script>