Use <string> serialization rules for computed value of reference filter

third_party/WebKit/LayoutTests/css3/filters/script-tests/filter-property-computed-style.js

 description("Test the computed style of the -webkit-filter property.");
 
 // These have to be global for the test helpers to see them.
 var filterStyle;
 var styleElement = document.createElement("style");
 document.head.appendChild(styleElement);
 var stylesheet = styleElement.sheet;
 
 function testComputedFilterRule(description, rule, expectedValue)
 {
     if (expectedValue === undefined)
         expectedValue = rule;
 
     debug("");
     debug(description + " : " + rule);
 
     stylesheet.insertRule("body { -webkit-filter: " + rule + "; }", 0);
 
     filterStyle = window.getComputedStyle(document.body).getPropertyValue('-webkit-filter');
     shouldBeEqualToString("filterStyle", expectedValue);
     stylesheet.deleteRule(0);
 }
 
-testComputedFilterRule("Basic reference", "url('#a')");
-testComputedFilterRule("Bare unquoted reference converting to quoted form", "url(#a)", "url('#a')");
-testComputedFilterRule("Multiple references", "url('#a') url('#b')");
-testComputedFilterRule("Reference as 2nd value", "grayscale(1) url('#a')");
+testComputedFilterRule("Basic reference", "url('#a')", 'url("#a")');
+testComputedFilterRule("Bare unquoted reference converting to quoted form", "url(#a)", 'url("#a")');
+testComputedFilterRule("Multiple references", "url('#a') url('#b')", 'url("#a") url("#b")');
+testComputedFilterRule("Reference as 2nd value", "grayscale(1) url('#a')", 'grayscale(1) url("#a")');
 testComputedFilterRule("Integer value", "grayscale(1)");
 testComputedFilterRule("Float value converts to integer", "grayscale(1.0)", "grayscale(1)");
 testComputedFilterRule("Zero value", "grayscale(0)");
 testComputedFilterRule("No values", "grayscale()", "grayscale(1)");
 testComputedFilterRule("Multiple values", "grayscale(0.5) grayscale(0.25)");
 testComputedFilterRule("Integer value", "sepia(1)");
 testComputedFilterRule("Float value converts to integer", "sepia(1.0)", "sepia(1)");
 testComputedFilterRule("Zero value", "sepia(0)");
 testComputedFilterRule("No values", "sepia()", "sepia(1)");
 testComputedFilterRule("Multiple values", "sepia(0.5) sepia(0.25)");
@@ skipping 58 matching lines @@
     "drop-shadow(1px 2px)", "drop-shadow(rgb(0, 0, 0) 1px 2px 0px)");
 
 testComputedFilterRule("Multiple operations",
     "grayscale(0.5) sepia(0.25) saturate(0.75) hue-rotate(35deg) invert(0.2) opacity(0.9) blur(5px)");
 
 testComputedFilterRule("Percentage values",
     "grayscale(50%) sepia(25%) saturate(75%) invert(20%) opacity(90%) brightness(60%) contrast(30%)",
     "grayscale(0.5) sepia(0.25) saturate(0.75) invert(0.2) opacity(0.9) brightness(0.6) contrast(0.3)");
 
 successfullyParsed = true;