Fix Background.isEmpty regression

tests/app/ui/tab-view/tab-view-tests.ts

@@ -4,7 +4,7 @@ import helper = require("../helper");
 import labelModule = require("ui/label");
 import stackLayoutModule = require("ui/layouts/stack-layout");
 import tabViewTestsNative = require("./tab-view-tests-native");
-import { resetStyleProperties } from "ui/core/view";
+import { unsetValue } from "ui/core/view";
 
 // Using a TabView requires the "ui/tab-view" module.
 // >> article-require-tabview-module
@@ -331,7 +331,7 @@ export class TabViewTest extends testModule.UITest<tabViewModule.TabView> {
         //console.log(`>>>>>>>>>>>>> nativeFont: ${fontToString(nativeFont)}`);
 
         console.log(`>>>>>>>>>>>>> RESET`);
-        resetStyleProperties(this.testView.style);
+        this.testView.style.font = unsetValue;
         assertFontsAreEqual(tabViewTestsNative.getNativeFont(this.testView), originalFont, "Font must be the original one after resetting the style.");
     }
 }

tns-core-modules/ui/styling/background-common.ts

@@ -316,8 +316,8 @@ export class Background implements BackgroundDefinition {
     };
 
     public isEmpty(): boolean {
-        return this.color
-            && this.image
+        return !this.color
+            && !this.image
             && !this.hasBorderWidth()
             && !this.hasBorderRadius()
             && !this.clipPath;