Import CSSWG Shapes tests

LayoutTests/imported/csswg-test/css-shapes-1/spec-examples/support/spec-example-utils.js

+function approxShapeTest(testId, linePrefix, epsilon, lineOffsets) {
+    var isPositioned = { 'relative': true, 'fixed': true, 'absolute': true, 'sticky': true },
+        loops = 0,
+        testDiv = document.getElementById(testId),
+        testOffset = isPositioned[getComputedStyle(testDiv).position] ? 0 : testDiv.offsetLeft,
+        firstLine = document.getElementById(linePrefix + '0');
+
+    function runTest() {
+        if (firstLine.offsetLeft == testOffset) {
+            // wait for the shape image to load and layout to happen
+            if (loops > 100)
+                assert_unreached("Giving up waiting for shape layout to happen!");
+            else
+                loops++;
+            window.setTimeout(runTest, 5);
+            return;
+        }
+
+        for (var i = 0; i < lineOffsets.length; i++) {
+            var line = document.getElementById(linePrefix + i);
+            assert_approx_equals(line.offsetLeft, lineOffsets[i] + testOffset, epsilon, 'Line ' + i + ' is positioned properly');
+        }
+        done();
+    }
+    runTest();
+}