Make sure <url>s are being serialized according to spec

LayoutTests/fast/css/getComputedStyle/getComputedStyle-background-shorthand.html

Index: LayoutTests/fast/css/getComputedStyle/getComputedStyle-background-shorthand.html
diff --git a/LayoutTests/fast/css/getComputedStyle/getComputedStyle-background-shorthand.html b/LayoutTests/fast/css/getComputedStyle/getComputedStyle-background-shorthand.html
index 8c236bb9336ff7f7cb6aa9efa1c1972d3b3252d9..cb731ad056d150d5a538b26ea24bc8e470f8dd11 100644
--- a/LayoutTests/fast/css/getComputedStyle/getComputedStyle-background-shorthand.html
+++ b/LayoutTests/fast/css/getComputedStyle/getComputedStyle-background-shorthand.html
@@ -30,35 +30,35 @@ shouldBe("computedStyle.getPropertyValue('background')", "'rgb(255, 0, 0) none r
 shouldBe("checkComputedStyleValue()", "true");
 
 e.style.backgroundImage = "url(dummy://test.png)";
-shouldBe("computedStyle.getPropertyValue('background')", "'rgb(255, 0, 0) url(dummy://test.png) repeat scroll 0% 0% / auto padding-box border-box'");
+shouldBe("computedStyle.getPropertyValue('background')", "'rgb(255, 0, 0) url(\"dummy://test.png\") repeat scroll 0% 0% / auto padding-box border-box'");
 shouldBe("checkComputedStyleValue()", "true");
 
 e.style.backgroundRepeat = "no-repeat";
-shouldBe("computedStyle.getPropertyValue('background')", "'rgb(255, 0, 0) url(dummy://test.png) no-repeat scroll 0% 0% / auto padding-box border-box'");
+shouldBe("computedStyle.getPropertyValue('background')", "'rgb(255, 0, 0) url(\"dummy://test.png\") no-repeat scroll 0% 0% / auto padding-box border-box'");
 shouldBe("checkComputedStyleValue()", "true");
 
 e.style.backgroundAttachment = "fixed";
-shouldBe("computedStyle.getPropertyValue('background')", "'rgb(255, 0, 0) url(dummy://test.png) no-repeat fixed 0% 0% / auto padding-box border-box'");
+shouldBe("computedStyle.getPropertyValue('background')", "'rgb(255, 0, 0) url(\"dummy://test.png\") no-repeat fixed 0% 0% / auto padding-box border-box'");
 shouldBe("checkComputedStyleValue()", "true");
 
 e.style.backgroundPosition = "right bottom";
-shouldBe("computedStyle.getPropertyValue('background')", "'rgb(255, 0, 0) url(dummy://test.png) no-repeat fixed 100% 100% / auto padding-box border-box'");
+shouldBe("computedStyle.getPropertyValue('background')", "'rgb(255, 0, 0) url(\"dummy://test.png\") no-repeat fixed 100% 100% / auto padding-box border-box'");
 shouldBe("checkComputedStyleValue()", "true");
 
 e.style.backgroundSize = "cover";
-shouldBe("computedStyle.getPropertyValue('background')", "'rgb(255, 0, 0) url(dummy://test.png) no-repeat fixed 100% 100% / cover padding-box border-box'");
+shouldBe("computedStyle.getPropertyValue('background')", "'rgb(255, 0, 0) url(\"dummy://test.png\") no-repeat fixed 100% 100% / cover padding-box border-box'");
 shouldBe("checkComputedStyleValue()", "true");
 
 e.style.backgroundOrigin = "content-box";
-shouldBe("computedStyle.getPropertyValue('background')", "'rgb(255, 0, 0) url(dummy://test.png) no-repeat fixed 100% 100% / cover content-box border-box'");
+shouldBe("computedStyle.getPropertyValue('background')", "'rgb(255, 0, 0) url(\"dummy://test.png\") no-repeat fixed 100% 100% / cover content-box border-box'");
 shouldBe("checkComputedStyleValue()", "true");
 
 e.style.backgroundClip = "padding-box";
-shouldBe("computedStyle.getPropertyValue('background')", "'rgb(255, 0, 0) url(dummy://test.png) no-repeat fixed 100% 100% / cover content-box padding-box'");
+shouldBe("computedStyle.getPropertyValue('background')", "'rgb(255, 0, 0) url(\"dummy://test.png\") no-repeat fixed 100% 100% / cover content-box padding-box'");
 shouldBe("checkComputedStyleValue()", "true");
 
 e.style.background = "border-box padding-box url(dummy://test.png) green 45% / contain repeat fixed";
-shouldBe("computedStyle.getPropertyValue('background')", "'rgb(0, 128, 0) url(dummy://test.png) repeat fixed 45% 50% / contain border-box padding-box'");
+shouldBe("computedStyle.getPropertyValue('background')", "'rgb(0, 128, 0) url(\"dummy://test.png\") repeat fixed 45% 50% / contain border-box padding-box'");
 shouldBe("checkComputedStyleValue()", "true");
 
 document.body.removeChild(testContainer);