CSS Transforms: Implement transform-style

LayoutTests/transforms/resources/parsing-test-helper.js

+window.expect = (function() {
+  var testElement = document.getElementById('target');
+
+  function assert_equals_or_matches(actual, expected, description) {
+    return expected instanceof RegExp ?
+        assert_regexp_match(actual, expected, description) :
+        assert_equals(actual, expected, description);
+  }
+  return function expect(property, camelProperty, input) {
+    return {
+      parsesAs: function(output) {
+        test(function() {
+          assert_true(CSS.supports(property, input), 'CSS.supports');
+          testElement.style[camelProperty] = input;
+          assert_equals(testElement.style[camelProperty], output);
+        }, '"' + property + ': ' + input + ';" should parse as "' + output + '"');
+        return this;
+      },
+      isComputedTo: function(output) {
+        test(function() {
+          testElement.style[camelProperty] = input;
+          assert_equals_or_matches(getComputedStyle(testElement)[camelProperty], output);
+        }, '"' + property + ': ' + input + ';" should be computed to "' + output + '"');
+      },
+      isInvalid: function() {
+        test(function() {
+          assert_false(CSS.supports(property, input), 'CSS.supports');
+        }, '"' + property + ': ' + input + ';" should be invalid');
+      },
+    };
+  }
+})();