fix error in visibility methods for empty node

src/element/visibility.js

@@ -15,8 +15,10 @@ function makeMethod(methodName, condition) {
         }
 
         const node = this["<%= prop() %>"];
-        const computed = computeStyle(node);
 
+        if (!node) return this;
+
+        const computed = computeStyle(node);
         // Determine of we need animation by checking if an element
         // has non-zero width. Triggers reflow but fixes animation
         // for new elements inserted into the DOM in some browsers

test/spec/element/visibility.spec.js

@@ -57,6 +57,10 @@ describe("show", function() {
             done();
         });
     });
+
+    it("does nothing for empty node", function() {
+        DOM.find("x-show").show();
+    });
 });
 
 describe("hide", function() {
@@ -97,4 +101,8 @@ describe("hide", function() {
             done();
         });
     });
+
+    it("does nothing for empty node", function() {
+        DOM.find("x-hide").hide();
+    });
 });