Fixed Array.Utils.GetFirst so it correctly handles a negative start…

… index. Fixes Container.getByName returning null and various other similar methods. Fix #7040

src/utils/array/GetFirst.js

@@ -15,6 +15,7 @@ var SafeRange = require('./SafeRange');
  *
  * Optionally you can specify a start and end index. For example if the array had 100 elements,
  * and you set `startIndex` to 0 and `endIndex` to 50, it would search only the first 50 elements.
+ * 
  * You can also specify a negative `startIndex`, such as `-1`, which would start the search at the end of the array
  *
  * @function Phaser.Utils.Array.GetFirst
@@ -23,39 +24,51 @@ var SafeRange = require('./SafeRange');
  * @param {array} array - The array to search.
  * @param {string} [property] - The property to test on each array element.
  * @param {*} [value] - The value to test the property against. Must pass a strict (`===`) comparison check.
- * @param {number} [startIndex=0] - An optional start index to search from. You cn also set `startIndex` to -1 to start the search from the end of the array.
+ * @param {number} [startIndex=0] - An optional start index to search from. You can also set `startIndex` to -1 to start the search from the end of the array.
  * @param {number} [endIndex=array.length] - An optional end index to search up to (but not included)
  *
  * @return {?object} The first matching element from the array, or `null` if no element could be found in the range given.
  */
 var GetFirst = function (array, property, value, startIndex, endIndex)
 {
     if (startIndex === undefined) { startIndex = 0; }
-    if (endIndex === undefined) { endIndex = startIndex >= 0 ? array.length - 1 : 0; }
-    if (startIndex === -1) { startIndex = array.length - 1; }
+    if (endIndex === undefined) { endIndex = array.length; }
 
-    var i, child;
-
-    if (SafeRange(array, Math.min(startIndex, endIndex), Math.max(startIndex, endIndex)))
+    if (startIndex !== -1)
     {
-        var step = startIndex < endIndex ? 1 : -1;
-        var count = Math.abs(endIndex - startIndex);
-        var index = startIndex;
-
-        for (i = 0; i < count; i += step)
+        if (SafeRange(array, startIndex, endIndex))
         {
-            child = array[index];
-
-            if (!property ||
-                (property && value === undefined && child.hasOwnProperty(property)) ||
-                (property && value !== undefined && child[property] === value)) 
+            for (var i = startIndex; i < endIndex; i++)
             {
-                return child;
+                var child = array[i];
+
+                if (!property ||
+                    (property && value === undefined && child.hasOwnProperty(property)) ||
+                    (property && value !== undefined && child[property] === value))
+                {
+                    return child;
+                }
+            }
+        }
+    }
+    else
+    {
+        if (SafeRange(array, 0, endIndex))
+        {
+            for (var i = endIndex; i >= 0; i--)
+            {
+                var child = array[i];
+
+                if (!property ||
+                    (property && value === undefined && child.hasOwnProperty(property)) ||
+                    (property && value !== undefined && child[property] === value))
+                {
+                    return child;
+                }
             }
-
-            index += step;
         }
     }
+
     return null;
 };