Properly managing overlfow-aligment for inherit and initial.

LayoutTests/fast/alignment/resources/alignment-parsing-utils.js

 function checkValues(element, property, propertyID, value, computedValue)
 {
     window.element = element;
     var elementID = element.id || "element";
     shouldBeEqualToString("element.style." + property, value);
     shouldBeEqualToString("window.getComputedStyle(" + elementID + ", '').getPropertyValue('" + propertyID + "')", computedValue);
 }
 
 function checkBadValues(element, property, propertyID, value)
 {
-  element.style.justifyItems = value;
-  checkValues(element, property, propertyID, "", "start");
+    element.style.justifyItems = value;
+    checkValues(element, property, propertyID, "", "start");
 }
 
-function checkInitialValues(element, property, propertyID, display)
+function checkInitialValues(element, property, propertyID, display, value)
 {
-  var initial = "start";
-  if (display == "grid" || display == "flex") {
-    element.style.display = display;
-    initial = "stretch";
-  }
+    var initial = "start";
+    if (display == "grid" || display == "flex") {
+      element.style.display = display;
+      initial = "stretch";
+    }
 
-  element.style.justifyItems = "center";
-  checkValues(element, property, propertyID, "center", "center");
-  element.style.justifyItems = "initial";
-  checkValues(element, property, propertyID, "initial", initial);
+    element.style.justifyItems = value;
+    checkValues(element, property, propertyID, value, value);
+    element.style.justifyItems = "initial";
+    checkValues(element, property, propertyID, "initial", initial);
 }
+
+function checkInheritValues(element, property, propertyID, value)
+{
+    parentElement = document.createElement("div");
+    document.body.appendChild(parentElement);
+    parentElement.style.justifyItems = value;
+    checkValues(parentElement, property, propertyID, value, value);
+
+    element = document.createElement("div");
+    parentElement.appendChild(element);
+    element.style.justifyItems = "inherit";
+    checkValues(element, property, propertyID, "inherit", value);
+}
+
+function checkLegacyValues(element, property, propertyID, value)
+{
+    document.body.appendChild(parentElement);
+    parentElement.style.justifyItems = value;
+    checkValues(parentElement, property, propertyID, value, value);
+
+    element = document.createElement("div");
+    parentElement.appendChild(element);
+    checkValues(element, property, propertyID, "", value);
+}