CSSStyleDeclaraction returns empty string

LayoutTests/fast/css/resources/parsing-text-rendering.js

Index: LayoutTests/fast/css/resources/parsing-text-rendering.js
diff --git a/LayoutTests/fast/css/resources/parsing-text-rendering.js b/LayoutTests/fast/css/resources/parsing-text-rendering.js
index 351f51edddcdc0b29d551d9b060b911b284a98f5..2104e14aaa89c5288a2d17158d92cf6af370e7dd 100644
--- a/LayoutTests/fast/css/resources/parsing-text-rendering.js
+++ b/LayoutTests/fast/css/resources/parsing-text-rendering.js
@@ -5,7 +5,7 @@ function test(value)
     var div = document.createElement("div");
     div.setAttribute("style", value);
     document.body.appendChild(div);
-    
+
     var result = div.style.getPropertyValue("text-rendering");
     document.body.removeChild(div);
     return result;
@@ -17,6 +17,6 @@ shouldBe('test("text-rendering: optimizeLegibility;")', '"optimizeLegibility"');
 shouldBe('test("text-rendering: geometricPrecision;")', '"geometricPrecision"');
 shouldBe('test("text-rendering: OptIMizESpEEd;")', '"optimizeSpeed"');
 
-shouldBeNull('test("text-rendering: auto auto;")');
-shouldBeNull('test("text-rendering: optimizeCoconuts;")');
-shouldBeNull('test("text-rendering: 15;")');
+shouldBeEqualToString('test("text-rendering: auto auto;")', '');
+shouldBeEqualToString('test("text-rendering: optimizeCoconuts;")', '');
+shouldBeEqualToString('test("text-rendering: 15;")', '');