DevTools: fix CSS.getComputedStyle protocol method

third_party/WebKit/LayoutTests/inspector/elements/styles-2/lazy-computed-style-expected.txt

 Tests that computed styles expand and allow tracing to style rules.
 
 ==== All styles (should be no computed) ====
 [expanded] 
 element.style { ()
 
 [expanded] 
 #inspected { (lazy-computed-style.html:15 -> lazy-computed-style.html:15:1)
     background: gray;
         background-image: initial;
@@ skipping 27 matching lines @@
 background-clip: border-box;
     initial - #inspected lazy-computed-style.html:15 -> lazy-computed-style.html:15:1
 background-color: rgb(128, 128, 128);
     gray - #inspected lazy-computed-style.html:15 -> lazy-computed-style.html:15:1
     OVERLOADED black - #inspected lazy-computed-style.html:10 -> lazy-computed-style.html:10:1
     OVERLOADED green - #inspected lazy-computed-style.html:5 -> lazy-computed-style.html:5:1
 background-image: none;
     initial - #inspected lazy-computed-style.html:15 -> lazy-computed-style.html:15:1
 background-origin: padding-box;
     initial - #inspected lazy-computed-style.html:15 -> lazy-computed-style.html:15:1
+background-position-x: 0%;
+    initial - #inspected lazy-computed-style.html:15 -> lazy-computed-style.html:15:1
+background-position-y: 0%;
+    initial - #inspected lazy-computed-style.html:15 -> lazy-computed-style.html:15:1
+background-repeat-x: ;

[dgozman, 2016/08/01 18:46:49]

Why empty? Is it a valid value?

[lushnikov, 2016/08/01 19:22:38]

That's consistent with window.getComputedStyle() method

+    initial - #inspected lazy-computed-style.html:15 -> lazy-computed-style.html:15:1
+background-repeat-y: ;
+    initial - #inspected lazy-computed-style.html:15 -> lazy-computed-style.html:15:1
 background-size: auto;
     initial - #inspected lazy-computed-style.html:15 -> lazy-computed-style.html:15:1
 display: block;
     block - div user agent stylesheet
 font-family: Courier;
     Courier - #inspected lazy-computed-style.html:10 -> lazy-computed-style.html:10:1
     OVERLOADED Times - #inspected lazy-computed-style.html:5 -> lazy-computed-style.html:5:1
 [expanded] 
 element.style { ()
 
@@ skipping 19 matching lines @@
 [expanded] 
 #inspected { (lazy-computed-style.html:5 -> lazy-computed-style.html:5:1)
 /-- overloaded --/     background-color: green;
 /-- overloaded --/     font-family: Times;
 
 [expanded] 
 div { (user agent stylesheet)
     display: block;