spelling: containing

Author: jsoref

test/unit/styling-cross-scope-var.html

@@ -881,7 +881,7 @@
 
   test('variable literal defaults can contain one (...)', function() {
     var b = getComputedStyle(styled.$.default3).backgroundColor;
-    assert.match(b, /rgb\(128/, 'literal fallback containin (...) not set');
+    assert.match(b, /rgb\(128/, 'literal fallback containing (...) not set');
   });
 
   test('variable values can be used with calc', function() {